If you want to wire up your rear fog lamp as another brake light where it brightens when you step on the pedal, you'd have to dig around the DIY section.
If you wanna do the easy way where the fog lamp acts as a static parking light that can be shut off along with the headlights, here is a write up from awhile back from forum member Cbtech:
DIY: Fog Light Hard Wire in less than 10 Minutes! W/Headlight integration!
Hopefully that helps!