scripting new plugin paths

I want to be able to dynamically include plugins in directories outside of the 'plugins' and 'stdplug' directories of the 3dsMax install directory. I would prefer to not have to add lines to the plugin.ini. Possibly temporary session paths called with preRenderScript from 3dsmaxcmd.exe command line.

I've looked everywhere for the last 2 days for information on this and found nothing. Any ideas?