Numptie of the highest order
Re: Fitting facelift A3/S3 headlights to a pre facelift 1998 A3
I think firstly you need to let us know whether they are xenon lights or not, if there xenon's I'd give up now to be honest it's a lot of work to get them working right as described above.
If there not and you can sort the wiring you only need to remove the old ones, cut a section out of the wing (only small from what's been said before) then fit them in. if you do a search for facelift lights I'm sure you'll find the old posts.
Might also be worth looking at the fitting xenon lights thread in the FAQ sure that'll have some pointers.