The early highline modules up to about 2005/2006 could be programmed independantly of a dealer as long as you had a fully working VAG Commander (as Darren has). You need this to be able to extract the SKC (immobiliser code) from you existing cluster and transfer it to the new along with the mileage.
Later versions of the cluster had a revised security method which most VAG Commanders can't access. So although you could buy a new cluster from a dealer, you couldn't program it. Even the dealers themselves now don't see your SKC code apparently when they perform the upgrade, as it's electronically transmitted by their VAS equipment straight from Germany and into the cluster via the VAS. The only option on the later cars is to have a dealer fit it (if you can pursuade them).
I was lucky and found a highline from a 2005 breaker car (same year as mine) with the correct part number from fleabay for the silly price of £20. I then proceeded to donate it to Darren for his car
(only kidding Darren
)