Well, I don't have iDefrag, so I'm not sure about that. Generally, you must boot from something other than your startup drive to optimize it. With TTP, you create an "eDrive" right on the hard drive that allows you to optimize. It's almost like partitioning.
As far as your bootcamp question, I won't have a clue. But, you need to provide more info ... unless you have a separate thread on that and think many thousands of people will be reading it and this one.
If you want to run iDefrag, try it out. There should be an option in it to create a bootable disc, according to their site. Their site also says it doesn't require a bootable disc, it can run itself before the system starts up I guess. It seems like once you click the option, you simply reboot and it will start up.
I can't be of much more help since I don't have the program myself, but their website's support should give you the help needed to run it properly.
The other option is as I said in the other thread, backup your data, re-install leopard with your install DVD, and run the boot camp assistant again. Hopefully if it runs from a clean install, there would be no problems.