well I mostly work with halo ce but I have halo 2 vista and just like messing around every once and awhile with it... :)

absolutely, i have been doing it very much recently, for instance i made the flood juggernaught for the lvl high charity by changing the biped of the flood carrier to it, lol now if only i could get it to fit through the doors and such, anyways the program you would want to use is gravemind, just google it its what im using only problem is it has alot of unknowns that i would really like to know.

Either meta swap or change those dependencies

You can find some interesting stuff when messing around with gravemind. Like on outskirts there are brute shots and brute plasma rifles in the map. No brutes though. You can also make the Shadow drivable in gravemind.

oh no i can top your brute stuff in outskirts, the biped and all animations and stuff for a brute is in cairo station, lol i turned all red elites into brutes and they beat the hell out of me the whole time, i kept turning corners and getting punched in the face by them, only diff they used plasma rifles instead of brute plasma rifles

You two don't realize the full not really awesome potential of gravemind other than biped swapping.

You can...
Edit it to dual wield other stuff like snipers, energy swords
Edit the unicode strings and change the subtitles tehe
Make hoggys fly
Fly pelicans
etc...