Some have used vag com or vag tacho I just went a got a ecu immo box and key for the chip it worked out cheaper:Reply i got when i asked:First I would find someone with vag-tacho to see if they can read the SKC from your immo box. As without this SKC recoding can't be done easily. If they can then just buy an ecu and recode with vag-com. Some mk3's won't let you read the SKC with vag-tacho and require some more specialist tools and I don't know many people who offer this service.Another option is replace the ecu with one with the immobiliser defeated.
It's not hard to do with vagcom, aslong as u have a matching key to immob box, if u don't it does get tricky recovering skc code.Anyone near by with vagcom? To help him out?