Yes it is possible to some degree. BAS did it.
Have a look at the randCivieInit.sqs located in the FX folder of the BAS_OPCPP.pbo:
_unit = _this select 0
_randInt = loadFile "\BAS_OPCPP\FX\randInt.sqf"
_randHead = [0,5] call _randInt
_randTop = [6,11] call _randInt
_randTrouser = [12,17] call _randInt
; head
call format ["_unit setobjecttexture [%1,{\BAS_opfor\civ\bas_a_face_%2.pac}]",_randHead,_randHead+1];
; top
call format ["_unit setobjecttexture [%1,{\BAS_opfor\civ\bas_a_civ_%2.pac}]",_randTop,_randTop-5];
; trouser
call format ["_unit setobjecttexture [%1,{\BAS_opfor\civ\bas_a_civ_%2.pac}]",_randTrouser,_randTrouser-11];
exit
The problem is you will need a model that supports this and some textures. Have a look at the BAS Opfor files. I experimented with this a little, one problem is that you can change the appeareance of a unit only for a few times (~5 times, this was related to a pivots thingy, has been some time since I had a look at it) and only the textures.
h
Edit:
You could also remote control other units, look for a mission called 'fake' I posted there:
http://www.sinewsofwar.com/forum/viewtopic.php?t=48&postdays=0&postorder=asc&start=0&sid=0e35e19b26cafb03baa91a18f7085106Later in the same thread I posted a 'changecloth' mission, using the bas functionality.
Hope this helps...
h