teamart, helmets and perf file you can easy update with carsetcreator 4 without having a problem! Pitcrews you can't update with carsetcreator cause the game crash when a car goes into the pits!
For teamart you load the tga or gpi into the right box and then you just press export and the teamart will be updated in the game!
Teamart is stored in the follow directory: menudata\pc\gp2001\images
they are all in gpi but your tga that you put in is converted into gpi !!!!
Hope it answered your question!