Yes, you can define multiple corner conditions in a single technology configuration file and select one corner condition among them when running MODELZEN to generate the models. Currently, MODELZEN generates models assuming only one corner condition at a time and you can run MODELZEN multiple times to generate multiple sets of models each corresponding to a different corner condition.
You can define a set of corner conditions using two dictionary variables named 'dev_model' and 'dev_corner' in the technology configuration file.
The 'dev_model' dictionary defines a set of SPICE statements that include the SPICE model libraries and define voltage and temperature conditions for characterizing the devices or circuits with SPICE. For example, the example technology configuration file located in ${XMODEL_HOME}/etc/tech_config.py has the following entries for dev_model['hspice']. In the same file, you can also find the equivalent entries defined for dev_model['spectre'].

dev_model['hspice'] = {
  "default" : """
.lib "/cad/tech/cmos014/hspice/mosfet_model.lib" TT
.lib "/cad/tech/cmos014/hspice/passive_model.lib" typ
.temp 25
""",
}

Variables can be embedded in these statements so that the actual content used in the SPICE characterization decks can change depending on the values of these variables. For instance, the following example uses three embedded Python variables, proc1, proc2, and temp, each specifying the library names to include and temperature value, respectively. For more information on how to embed Python variables within a string, please refer to the EmPy documentation (link).

dev_model['hspice'] = {
  "default" : """
.lib "/cad/tech/cmos014/hspice/mosfet_model.lib" @proc1
.lib "/cad/tech/cmos014/hspice/passive_model.lib" @proc2
.temp @temp
""",
}

The 'dev_corner' dictionary defines the values of these variables. The example below defines the values of the variables proc1, proc2, and temp as 'TT', 'typ', and 25, respectively, so that it has the same effect as the first example without the embedded variables.

dev_corner['hspice'] = {
  "default"  : dict(proc1='TT', proc2='typ', temp=25),
}

It is also possible for the 'dev_corner' dictionary to define multiple sets of the variable values, each indexed by a user-defined corner name. For instance, the example below defines three corner conditions, 'TYPICAL', 'FAST' and 'SLOW', in addition to the default corner 'default'. And for each corner condition, the variables proc1, proc2, and temp have different values. For example, for a corner named 'FAST', the values of proc1, proc2, and temp are 'FF', 'best', and -30, respectively.

dev_corner['hspice'] = {
  "default"  : dict(proc1='TT', proc2='typ', temp=25),
  "TYPICAL"  : dict(proc1='TT', proc2='typ', temp=25),
  "FAST"     : dict(proc1='FF', proc2='best', temp=-30),
  "SLOW"     : dict(proc1='SS', proc2='worst', temp=125),
}

You can select the desired corner condition among the ones defined within the technology configuration file by using the '--corner' option on the command line or defining the 'Simulation Corner' option located in the 'Simulation' tab of the MODELZEN's GUI dialog window.

$ modelzen circuit.sp -c tech_config.py -o model.sv --corner FAST

When you don't explicitly specify the corner condition, MODELZEN assumes a corner named 'default'. The example below shows a way to make one of the user-defined corner conditions the default one. Since MODELZEN's technology configuration file uses the flexible Python syntax to define the options, there are multiple ways to achieve the same results.

# user-defined corner conditions
dev_corner['hspice'] = {
  "TYPICAL"  : dict(proc1='TT', proc2='typ', temp=25),
  "FAST"     : dict(proc1='FF', proc2='best', temp=-30),
  "SLOW"     : dict(proc1='SS', proc2='worst', temp=125),
}

# default corner condition
dev_corner['hspice']['default'] = dev_corner['hspice']['FAST']

Yes, you can define multiple corner conditions in a single technology configuration file and select one corner condition among them when running MODELZEN to generate the models. Currently, MODELZEN generates models assuming only one corner condition at a time and you can run MODELZEN multiple times to generate multiple sets of models each corresponding to a different corner condition.
You can define a set of corner conditions using two dictionary variables named 'dev_model' and 'dev_corner' in the technology configuration file.
The 'dev_model' dictionary defines a set of SPICE statements that include the SPICE model libraries and define voltage and temperature conditions for characterizing the devices or circuits with SPICE. For example, the example technology configuration file located in ${XMODEL_HOME}/etc/tech_config.py has the following entries for dev_model['hspice']. In the same file, you can also find the equivalent entries defined for dev_model['spectre'].

dev_model['hspice'] = {
  "default" : """
.lib "/cad/tech/cmos014/hspice/mosfet_model.lib" TT
.lib "/cad/tech/cmos014/hspice/passive_model.lib" typ
.temp 25
""",
}

Variables can be embedded in these statements so that the actual content used in the SPICE characterization decks can change depending on the values of these variables. For instance, the following example uses three embedded Python variables, proc1, proc2, and temp, each specifying the library names to include and temperature value, respectively. For more information on how to embed Python variables within a string, please refer to the EmPy documentation (link).

dev_model['hspice'] = {
  "default" : """
.lib "/cad/tech/cmos014/hspice/mosfet_model.lib" @proc1
.lib "/cad/tech/cmos014/hspice/passive_model.lib" @proc2
.temp @temp
""",
}

The 'dev_corner' dictionary defines the values of these variables. The example below defines the values of the variables proc1, proc2, and temp as 'TT', 'typ', and 25, respectively, so that it has the same effect as the first example without the embedded variables.

dev_corner['hspice'] = {
  "default"  : dict(proc1='TT', proc2='typ', temp=25),
}

It is also possible for the 'dev_corner' dictionary to define multiple sets of the variable values, each indexed by a user-defined corner name. For instance, the example below defines three corner conditions, 'TYPICAL', 'FAST' and 'SLOW', in addition to the default corner 'default'. And for each corner condition, the variables proc1, proc2, and temp have different values. For example, for a corner named 'FAST', the values of proc1, proc2, and temp are 'FF', 'best', and -30, respectively.

dev_corner['hspice'] = {
  "default"  : dict(proc1='TT', proc2='typ', temp=25),
  "TYPICAL"  : dict(proc1='TT', proc2='typ', temp=25),
  "FAST"     : dict(proc1='FF', proc2='best', temp=-30),
  "SLOW"     : dict(proc1='SS', proc2='worst', temp=125),
}

You can select the desired corner condition among the ones defined within the technology configuration file by using the '--corner' option on the command line or defining the 'Simulation Corner' option located in the 'Simulation' tab of the MODELZEN's GUI dialog window.

$ modelzen circuit.sp -c tech_config.py -o model.sv --corner FAST

When you don't explicitly specify the corner condition, MODELZEN assumes a corner named 'default'. The example below shows a way to make one of the user-defined corner conditions the default one. Since MODELZEN's technology configuration file uses the flexible Python syntax to define the options, there are multiple ways to achieve the same results.

# user-defined corner conditions
dev_corner['hspice'] = {
  "TYPICAL"  : dict(proc1='TT', proc2='typ', temp=25),
  "FAST"     : dict(proc1='FF', proc2='best', temp=-30),
  "SLOW"     : dict(proc1='SS', proc2='worst', temp=125),
}

# default corner condition
dev_corner['hspice']['default'] = dev_corner['hspice']['FAST']