Making a custom player model?

Hey guys,
Do any of you know of a good tutorial that shows how to make a custom player model or skin for tf2? Like for example the creators of Fem Scout, Sniper Spy, etc that replaced the normal male versions, or something like this (definitely not into the style, just an example)

There’s someone over at GameBanana named King Raptor that might be able to help. I think Sergeant Joe also does/did some TF2 character stuff in the past, but I’m not sure 100% on that.