I wouldn't count on any last minute practice time coming available. The track sponsored test and tune days are set "in stone" pretty early on in the year and I don't believe they change very often. I have a friend who is flying up from Dallas to test his Formula Mazda at Infineon that day. I doubt he'd be very happy to find out that he'll be sharing the track with the likes of us!!
I'm guessing, here, but I'll bet that the insurance that the track uses for its own sponsored test days has a condition for licensed drivers. That is, drivers licensed with a nationally or internationally sanctioned racing body - SCCA, NASA, FIA, IMSA, etc. It would probably take an act of god to relax that requirement. The Lemons crew runs with their own insurance, I'm sure, that accounts for drivers who are licensed differently, but are kept on a much shorter leash.
So, if you REALLY want to drive Infineon before the Lemons green flag waves on March 6th, my advice is to get on board with one of the track-day outfits mentioned here. You can use a street car. What will be important is to just get familiar with the track layout, line, elevation changes, etc. You can get past the sensory-overload stage pretty quickly, and you don't need a race car to do that.
Just one guys opinion.
Cheers,
Dean
PS - I offered up my "write up" of Infineon on another thread. I'll offer it here, too. If you've never driven Infineon and want some color commentary on it, you can use that (just PM me and I'll send it to you) and watch some in car video at www.molaps.com
Also, Jim's class sounds like an excellent way to get some good advice smushed into your skull just before you put on your helmet.