I think this is what you're looking for; just needs to be ported to amxmodx:
http://djeyl.net/forum/index.php?showtopic=42303
Someone tried to port it but didn't quite finish it:
http://forums.alliedmods.net/showthread.php?t=15955
Just a warning if you plan on doing this: you should have fastdl or else it will take forever, and I mean forever to download the weapon models for the client. The more models you use the more the client has to download. Weapon models can get large to download when you have to download v, p, and w models.