Bare with me as I'm new to this myself.
first you'll have to unpbo the warfare.pbo, then open the newly created warfare folder and into mpmissions. Open the appropriate mission, the 16 or 32 player vs.
next look in common/cfg, and configairfactory. you will see some lines like this
_u = _u + ["AH1W"]
_d = _d + [Localize "STR_DN_AH1Z"]
_c = _c + [7500]
_m = _m + [7500 + (westBarracksCosts Select WPILOTTYPE) * 2]
_t = _t + [55]
_p = _p + [50]
_o = _o + [false]
_i = _i + ["\ca\air\data\ico\ah1z_CA.paa"]
change the "AH1W" to "classname of v-22", For the name to show up in the dialog ingame this is what I did. Change the Localize "STR_DN_AH1Z" to Localize "STR_V22", then go back out to the stringtable.csv and add this line:
STR_V22, V-22 Osprey
the +[7500] is the base cost for empty unit, change this to whatever you wish, repack the warfare file and your good to go. Also I would suggest making a backup of the originall pbo as well.
hope this helps, as I said I'm still new to this myself and learning as I go along.
Almost forgot: for the right picture to show you'll have to change the parameters for the paa file to match the one for the Osprey, sry sure what that is at the moment. I'd have to ask Gnat or unpbo the osprey to look at the paa files.
Edit: try this + ["\ca\gnt_v22\GNT_v22pic.paa"]