Lance,
If I were going to attempt that deal, I sure would remove the flywheel and have the layout and drilling done on a Bridgeport with digital scales or something similar. The next best thing would be to layout the holes with layout dye, straightedges and a digital caliper or two on the bench.
This might seem like overkill, but the huge rotating mass needs to be pretty well centered. I haven't seen this problem addressed here before so it makes me think there is a pressure plate available that will do the job and bolt to the existing flywheel...but I haven't done the T5 swap myself.
Stuart