If it is rigged to the HL2 skeleton, and has the right animations, go ask in the Lua section.
If it is rigged to the HL2 skeletion, but has either the wrong or no animations, then you need to decompile the model, add the animations to the .qc and compile, then you go ask in the Lua section.
If it is not rigged to the HL2 skeleton (and therefore has no or the wrong animations), then you need to decompile the model, rig and maybe change the shape of the model to make sure it fits the skeleton, add the bones, hitboxes and animations to the .qc and compile, then you go ask in the Lua section.