I made a "support" stand for the CD-Rom out of an L shaped aluminium thingie, and also reseated the HDD. Be aware that you do not only get a slim CD drive, but also a connector that gives you a 3,5 IDE, and Floppy power connector for it. Just use any (long enough) Y Floppy Power Kable to power your CD-Rom from the Floppy power connector.
Maybe have a look at my signature for some ideas how to do/place things. (Sorry it's all german, but the photos should be "readable" for everyone.
Have fun while building it :-D