I guess you don't need to use WorkBench then. Just create your structure in the editor (or write a script, which should include also information about the mesh), save it as an .scm file and run 'sde -e -l yourfile.scm'. Afterwards, all you need is to create a simulation command file that will load the previously created structure and run 'sdevice yoursimulation.cmd'. More info about creating the scripts can be found in Sentaurus manuals - they also contain some examples.
Regards