Need some pointers on head switching / adding props to ragdoll models.

A few days ago I bought Garry’s Mod, and found I was interested in learning how to make my own ragdoll models. I’ve done a lot of research, and so far I’ve been messing around with vtfedit, and hexing. Since I don’t own hl2, tf2 or. Cs, my only default models were the ones that came with sfm (tf2 and hl2 models). I’ve downloaded tons of custom models for gmod and sfm alike, and so far I’ve only successfully copied a model, hexed the model, and edited some. Vtf and. Vtm files in order to recreate the same model with a new skin, so as not to overwrite the original. I have yet to try making multiple skins for one model by editing Vtm. I have seen many tutorials on how to make my own model with blender, and compiling, but before I walk into that shit storm I want to be able to successfully edit the models I already have. Like it says up above, I was wondering if I would be able to switch heads on a ragdoll through hexing and vtfedit using models I already have, or would I need to decompile, and start rigging, meshing, and all that happy goodness? Btw, I’m sorry if this thread has been mass posted already. I’ve seen many how to threads, but I need something a little more specific and less general.

You may want to ask over in the modeling section.