http://www.fpsbanana.com/tuts/9470

Seems to work pretty ok.

if you just want solid gold like the Golden Wrench, just extract the GW skin and rename it as the appropriate weapon

well, since you didnt bother to make links, i didnt bother to follow them

anyway, if you want parts of a weapon gold, do what ippe said. if you wand solid gold, do what i said. if you dont know how to skin, hit the goddamn "tutorials" button

That tutorial is horrible. If you want to do it good you need appropriate VMT shaders for the desired effect. It will always look flat if you just give it a goldish color. (Well depends on the default shaders that are used on the skin, but it will look off in most situations)