At Vance, our casual LT flight commander requests the waivers... If you have your PPL, you'd talk to her and she requests/fills out paperwork. Last I heard, it takes a week or two to go through.
I had a good time at IFS; I was the last class to go through without the waiver. It was the first time I'd ever gotten to fly multiple days in a row and it wasn't all that stressful. Sure, it probably won't help a TON with UPT, but it's a low to mild stress environment with pretty good food and you get some time in a neat airplane. If you've never flown the "military" way before, it might give you a really basic understanding of the pattern, departures, arrivals, and checklist usage (challenge/response, callout items). It's also a good way to learn to do things the way you're told and not how you were taught in the past. Overall, a solid program, fun flying, you'll make money, and the food is good. If you're casual and just sitting around, it might be a good deal to go. If you're married or flying on the weekends, you probably don't wanna go. If you haven't flown in a long time, you might wanna go just to knock the rust off. Just my .02