Megapack helmets

I have downloaded that megapack 2003, they use that new hans system, and stuff, and they use a white fantasycar in the back. I replaced it with the williams from 1993 (senna and hill). I already had it in my old cars.wad. The car is a little bit different than normal F1-cars. So I have to move the helmet forward. I used the cameditor from lo2k before the megapack. Now I try to do it again, but there doesn't happen anything?