Plugin Path Environment Variables

Anyone know if there is an WIndows Environment Variable that 3dsMax looks for to find other plugin locations? I've read some posts about adding the path to the windows "path" environment variable.

I don't want to edit the plugins.ini because many people will be rendering with the same system and they won't need the same custom plugins. It is already working for Maya by setting temporary Enviroment Variables. What variables can I use for 3ds Max?