Good advice from Dave. I also have the newbonneville.com thumb bolts, and they work pretty well. If, even with putting pressure on the seat you still have trouble lining it up you can take out one or both of the rubber grommets in the seat to give you a bigger hole to target the bolt into. If you do that, tho, remember that the thumb bolts are aluminum, so they can get stripped a bit if the seat moves around, so set them very tight (hand tighten only!) NewBonneville also sells nice matching hand turned bolts for both side panels, which I also find helpful. The package is a bit pricey, but they give you a discount for buying the two sets (seat and side panel) together.
There are other ways I have tried and they work, sort of, but I find the bolts from Newbonneville the least aggrevating. As Dave said, there are a few long threads on this topic. Search for "seat bolts" or "seat" on this forum and you will find them.
Take care,
Monte