I've been hacking away at this and I finally got the theme to work correctly when applied to a custom Rhodium-based ROM. I'm using Juicy 8. It was all a matter of locating the right Rhodium cab files.
1. Install JMZ's Sprint clock for Rhodium cab: Jmz Sprint Clock TF3D 2.CAB
http://forum.ppcgeeks.com/showthread.php?t=62770
2. Install S2W's Blackdrop Revised cab.
3. The Blackdrop theme was designed for a stock Sprint ROM so the slider will be off-center. To fix this I installed NRGZ28's Transparent Slider (for Rhodium) cab. I found it over at xda-developers, but can't seem to find the thread at the moment.
4. I also had a gray bar at the top of the window. To clear this I used Dutty's NoTopCurtain cab.
http://forum.xda-developers.com/showthread.php?t=509360
Here's a screenshot of the result.