TT pedals aren't actually alloy, they are stainless steel.
The brake and clutch should fit straight on, but the accellerator pedal on the Mk3 is flatter than the Mk4/TT pedal, so you need to flatten the stainless part slightly.
Take the rubber bits off, place a block of wood over it, and hit the wood with a hammer to flatten it...then it should fit.
I had TT pedal covers on mine before I fitted the Mk4 Anniversary covers.
