Rerig a model on Hl2 skeletons?

Im trying to make a Player model for Garrysmod one problem is that its rigged on a Custom Skeleton

Is there any way to rerig it on the hl2 Skeleton?

The process is a pain in the ass.
First you’ve got to decompile the model (I’m assuming you’re doing this for Serah?) so that you have the base .smd that was used. Import that SMD into your favorite 3D modeling program, and completely strip away the skeleton.
Now, you get to import the ragdoll.smd from your favorite Half-Life 2 character (they all use the same skeleton). More than likely, the model will not fit the skeleton at all. Since you want to use the player animations, you can’t really alter the skeleton, or the animations will be really odd. So chances are, you’ll have to rescale the model and probably manually move several vertices.
After that, you have to edit all of the vertex groups on the base model to properly reflect the new skeleton, so that the model deforms correctly when bones are moved.

Then you get to export it, and you have to include all of the animation .smds that the Half-Life 2 characters use (should be in the Source SDK content folder somewhere). I’m rather hazy on this matter, as I’ve never bothered to work on it at or past this point.

A lot of people seem to want everything and its grandmother turned into a playermodel or NPC, but very, very few of them know how irritating the process of doing so actually is… especially after you’ve already made a completely new skeleton for the model in question.

its gonna be a pain in the ass to do it but it will be worth it