im currently 10% flashing into cooked dcd 3.0 rom....
install official rom first
then follow directions here
http://forum.xda-developers.com/showthread.php?t=376207
*edit
i forgot to say YES, its worth the upgrade...damn this is nice, all htc dark modded on wm 6.1 on new rom, im recooking a new rom without that stupid voicedial app and including the startup animation, so one more flash and i should be happier