This is more involved procedure than flashing a ROM but a rewarding one. The overall smoothness running this mod is notable.
Check out the forum post here: http://forum.xda-developers.com/showthread.php?t=1943896
I'll try to expand on his directions here and there but basically, you have to prepare the card with 2 active partitions one NTFS/exFat/FAT32/etc and one ext2 or ext4 with disabled journaling (post 3-- if you don't do this on CleanRom you get an "Encryption failed"), run the instructions on ADB/Terminal.
I haven't updated Roms or other general maintance though I plan to provide feedback once I do.
EDIT: There have been a lot of updates. There is an alternate version and you now just have to flash versus terminal terminating. http://forum.xda-developers.com/showthread.php?t=1950039 A different version, perhaps its a bit more robust than previous versions.
12/12/12 Update: So this crashed on me hard after a power cycle. It turns out that I had a failing MicroSD but it did happen on vacation and it was a pain in the ass when it doesn't turn on.