supposedly you can't install SP1 with boot camp. Technically, you don't even need boot camp to install windows. All you have to do is create a partition and then install Windows on it, so you should be able to install an old version of Windows and then upgrade to SP2 (if MS still has that download available). Assuming you have Leopard, you'll just need to use the Leopard disk to install the drivers. Without using boot camp to install, you'll have to get a program that will allow you to boot into Windows. I don't know the name offhand, but if you do some searching, you'll find a thread with the info.
That should work, in theory, but I've never tried it personally. All you can do is try.