Mod it just like you would a normal pc version but a little differently.
1. Extract with isobuster and save your LBA
2. Use IMG Tool 2.0 and open GTA3.IMG which should be located in the MODELS folder (you might need to delete the files then add)
3. Replace the files you want and rebuild archive
4. Rebuild the game image according to LBA using either cdvdgen from sony or cdgen 3.0 (i prefer sony cdvdgen)
5. Save to IML with cdvdgen or save to image with cdgen
6. Use IML2ISO or another program to make an ISO if using sony cdvdgen and burn
Now if you don't want to go through the whole rebuilding process just make sure you're not making the GTA3.IMG bigger. Extract ONLY the GTA3.IMG file, and do steps 2 and 3 then use a program like ISO Relinker or Apache 3 to replae the file in the ISO, then burn.
Now a big problem is how many polygons the car or object is. If the mod has too many polygons the frames will be unbelievably slow or the game will just freeze. If this happens you might not be able to use that mod.
LET OP : Deze mod is op eigen gevaar !!
Deze mod heb ik nooit uigeprobeerd !
Als de gta sa crasht dan draai ik er niet voor op
Bij dez een waarschuwing !!!! : LET OP