here's a quick tutorial from tha masta...
1. Get Kam's GTA Tools for 3DS Max
2. Load Player.dff W/ DFF I/O and make sure the A (Auto-Skin) is ticked!
3. Hide ALL the player.dff you loaded
4. Load Your New Model...(Pigsy or whatever you want)
5. Position the bones or...the mesh itself in some cases...to be like Player.dff's
6. unhide player.dff's MESH not the bones
7. Highlight player.dff's Mesh and select the vertices in mesh edit and delete all his verts
8. click the attach button under mesh edit on the still vertice-less player.dff and attach your model
9. Under Skin you can edit the sections by clicking Edit Envelopes, ticking Vertices and if you want to select a whole area of verts you can tick By Element as well, then you click what bone you want to edit in the list (L Calf), and select the area for that selected bone
10. Under Skin Mod - Weight Properties, set Abs Effect to 1.0, and tick Rigid
11. Tada that bone should move the part of the mesh you assigned it to
Note: You may need to redo ALL of the mesh sometimes for the rigging...it takes time but it's worth it
12. Unhide all, (assuming you've already deleted your new model's old bones)
13. Select your new model, and player.dff's bones
14. open the DFF I/O again and export the model for whichever gta you have, uncheck MMC...hit export bone/skin and yay have fun...
Sorry this does not have any pictures, I just felt likes people should atleast know a little bit about modding again to get people to stray away from me since I'm really like never here anymore....and I feel like people forgot how to do this so yeah