They use this system in CoD2. It works pretty well, although might be hard to implement for BF2, nothing that there are indeed certain restrictions when modding. Who knows, though, maybe the coders are up to it. Technically, anything should be possible with the Python system in base, but there's modding a game and there's rewriting it. 
"I never knew I had it in me!" - C3PO
"Charging into the detention block wasn't what I had in mind!" - Han Solo
"I'll... I'll turn you all into fish!" - Edward Elrich