I've always fancied this little mod after seeing your Ed. The only bit that put me off was dropping the headlining to run the feed wire down to the rear. Is it much of a job?
Did you drill holes and fit the LEDs in the rears then Eddie?Then just take the supply from the front LEDs?
http://www.ebay.co.uk/itm/VW-Golf-mk5-Rear-Interior-Light-with-Ambient-Lighting-/130808593885?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1e74ccbddd