Use one of the following values with the 
" mpmorph [character type]" code:

alien 
apesuit 
chestburster 
combatsynth 
convict 
drone 
droppilot 
drunkardtechmale 
eisenberg 
exosuit 
facehugger 
femalelabsynth 
femalelabtech 
grenadier 
guard 
guard1 
guard2 
guard3 
guardofficer 
harrison 
hazmat 
heavypredator 
laboror 
lightpredator 
malelabsynth 
malelabtech 
marine 
marine duke 
mccain 
meanguard 
merc1 
merc2 
merc3 
merc4 
mhawkpredator 
minigunner 
obrian 
officer 
pocguard 
pocofficer 
praetorian 
predalien 
predator 
pulseriflegirl 
pulserifleguy 
queen 
railgunner 
runner 
rykov 
rykovjr 
sadargunner 
scientist 
scientist1 
scientist2 
scientist3 
scientistchief 
smartgunner 
smuggler 
tamiko 

note: these cheats work only for the european version of the game