Just a heads up on this. I've been looking into retrofitting TPMS to my 2010S3, as the profile on the tyres are pretty low and does not take much pressure loss before they would be on the road!
So I was all set to follow this:
Enabling TPMS on a 59 Plate; How-To Addendum
However I then came across this:
TPMS - Roccopedia
which is using VCDS to code for TPMS and using VCDS to reset the system(rather than installing a button). You do need the newer long coding MK60 ABS module to carry it out though.
Well, anyway followed it, spent some miles having the system learn the wheel speeds/vibration amounts etc, then let one front tyre down about 10psi and after 2 miles TPMS warning/bong on the DIS! Woo, TPMS for free!! Then just used VCDS to reset it and its back learning again.
You guys might know about this. but thought I'd flag it up as it works! I might still do the button (fill a blank on the dash), but we will see.
Hope it helps!