Source CAN do coloured spec, but not in the usual way. It's been a while, but if I remember right the green channel of your spec map controls the saturation of the specular highlight, which is based on the diffuse colour. It's not great and you usually have to really ramp up the brightness of the spec map to see it, but…
spec is source episode 1 engine. No coloured spec and no combination specular/env map. Told the guy to move to orange box. Wont. So yeah it's gunna look a little like plastic even when finished. :(
Dude Brad, great work on the wrench! Probably the best one I have seen. But Clockwork brings up a good point about the spec map. Even in the ref the spec on the painted area seems a tad higher than on the model.
Jesse, it might be a good idea to use a RGB channel texture for your spec, spec mask and variation, having 3 textures in one map could make it a bit more efficient. looks like there are lots of options for that material, should prove pretty versatile.