I'm pretty certain that there isn't any way to pass arguments in the PP2 file.

If there was you'd find them in the sys.argv list.
Poser does actually set argv[0] to the filename of the script.

One way round this would be to use a number of small scripts that just call a method with different arguments.
The method that actually does the work would be in another PY file, the calling scripts would need to import it.