UPDATE 7/11/09: Procedure working great: post here.
Everyone’s getting antsy about on-device debugging with SDK 3.0, which as most of us know broke our preferred method. It looks like the only answer may be to use an outdated version of the SDK, but I’m going to look into it asap. My plan was to use an external drive to install a throw-away virgin copy of OSX. That way, I can experiment and play, and just trash things that don’t work so that I know EXACTLY how to install properly. Incidentally, I also need to use this setup for a few similar things at work. The problem is that my MBP’s DVD burner is a piece of crud. I say that conclusively because everyone else with a Macbook Pro has the same problems after some time. At this point, it still READS DVDs (mostly) but it can’t burn to save its life. My OS disks got horribly marred by someone I loaned them to, and while I had backup images on an external drive, they’re clearly not helpful if I can’t burn disks :). Today though, I’ll have access to fresh, OEM disks, so I’ll get my install going, image it with SuperDuper or Disk Utility, and that should be the ticket. I’ll keep you updated, but I expect that I might be able to start working on this after work tonight or tomorrow sometime. In the mean time, the best resource on this problem (and the one that I plan to use to get some procedures going) is http://iphonesdkdev.blogspot.com/.