One option is to boot using your rescue CD. If you follow the prompts, you will be dropped off at a command line. This might not be terribly useful, though, because you're using the kernel on the rescue CD to boot, not the kernel you have installed on your system. But, once your looking at your system, take a peek at /etc/modprobe.conf. You may be able to remove something from there that gets you past the point at which your boot process hangs.