Custom models

I watched a movie from the U tonight I'd never seen (HL2DM Trailer by Cartel | Talented). In it, he had a custom model/animation on his grav gun with magic hands instead of the gun. Here's a screenshot: So how would I go about doing this? I'm a wizard and can do that IRL, so I have to do it in-game, as well.

HALP http://www.fpsbanana.com/skins/41127

Thank you so much! I love them. I feel incredibly wizardy when I play now, it's delightful.

Here's something for you, too. I never posted it but I did make it.