T4 key recode

I have a 2000 model T4 2.5 tdi that has a fault in either the reader coil/immobilser box.Vag have quoted me about £140 for the 2 parts but the dealer in my area can't recode my key,i would have to travel over 50 miles with the van,but as it won't start that is out of the question.Will the keys need to be recoded after fitting the new items?I have vagcom and was wondering if i can use that to do it?but read somewhere that i would need a list of number such as the 'skc-workshop code-and something else'.Anyone help?