This is possible starting from Tecnomatix V13.1
You can check in the Tecnomatix.NET.chm in the What's New section:
Use the LoadDataFromFile or LoadLineSimulationDataFromFile methods of ITxOfflineGlobalServicesProvider to load a psz file in Process Simulate Standalone. To save the changes to a loaded psz file, call to the SaveDataToFile method.
The same functionality is also available on Process Simulate on eMServer platform – refer to the LoadDataFromFile, LoadLineSimulationDataFromFile and SaveDataToFile methods of the ITxEmsGlobalServicesProvider interface.
It is now possible to get the full path of the currently loaded data file (psz, psz-tc or cell) using the FinalDestination property of the TxDocument class.
There is a command "Import pszx to Current Study" that imports a study to the current one. To generate a .pszx file use the "Save As" command and choose the relevant "Save as type" from the Save As dialog.