Yes brother,
You can have any model as a character, i have done sometime ago a tank enemy.
The procedure is very simple, just create the model, the animations, then use a script for it.
I found this script (it`s a very good script for tank):
http://forum.thegamecreators.com/?m=forum_view&t=114439&b=24
But you need to have a good knowledge of scripting to change this script and adapt it for your needs.
First you have to edit this helicopter fpi to make it stay on floor (instead of flying)
And one important thing to know is that FPSC only reads bone animations for characters.
I mean that any animation on this vehicle must be done through bones.
Goldenye 007 N64