Well, I rigged up a way to access CD-Rs. I have a power splitter on the power supply that goes to the hard drive go to a PC DVD-ROM drive, and I'm using the IDE ribbon from the Xbox DVD drive. To access the second drive, a legit Xbox disc has to be in the real Xbox drive, and the yellow power cable for it also has to be plugged in. Works great for VCD/SVCDs. =)

Though, you can actually buy on eBay DVD drives with special firmware to work in Xbox and support all media, which would be easier and more convenient in the long run.

For the most part, using burned CDs/DVDs in consoles is only for the purpose of piracy. As such, this thread is closed.