Its on the Market. Just called DroidX Bootstrap. Rubix is awesome. I love it. Download this on your DroidX to root it easily:
http://dl.dropbox.com/u/114466/z4root.1.3.0.apk
After that, there are plenty of posts on how to put Rubix 1.9.0 (assuming you are using the newest .340 OTA patch from Verizon) on your phone. Bootstrap your recovery with the DroidX Bootstrap app (it is paid, but needed nad worth it), reboot into recovery. Clear your data and cache and then choose "install zip from SD Card, choose zip and use the Rubix file you downloaded to your SD card. There are much better instructions in the threads from Drod2169 where he posted the ROM.