Configuration specific properties cannot be captured.
However, there are some methods available that will allow Configuration Specific Properties to be populated:
If a custom property exists with the same name as the configuration specific property, and has been captured, the driven value will be populated in all properties with that name.
The setting "Drive custom properties in all configurations" must be checked for Configuration Specific Properties to be driven. See SOLIDWORKS Settings for more information.
Apply the Generation Task Set Custom Property to the models that require the Configuration Specific Custom Property.
This task can create a new property in the model and has a property to set if this is to be Configuration Specific.