I'd think the manifold will be one of the biggest issues, plus oil lines for the turbo (maybe you can just tap the sump for those - not sure if you'd need a filter or not though?). Will the IS ECU be happy with an 8psi turbo strapped to the engine, or is it going to need piggybacking to fuel it properly?
I've often thought that the 1GFE could really do with a turbo - nothing big or offensive, but more a small, quick spooling, lowish pressure turbo, something that feels OEM like a Golf 1.8T does. I'd rather that than a supercharger, mainly just because I don't want the noise of a 'charger (I know some love it, but I prefer a little, unobtrusive, turbo whistle, than the whine of a supercharger)