I've done a bit of stuff with UI's in EQ Live. I would suggest since not alot is known yet about EQ2 UI's, to maybe play around with some EQ UI's just for practice. I was using a downloaded UI and have been doing the updates on it myself and changing certain things to make it better for myself. When I started I was a complete newbie to XML and have figured out quite a bit by picking through the xml coding of files in the UI's.

And I also found a very nice program for helping me to learn certain things. I can't find the link at this time but if you look for a program called SIDL, this works great for EQ Live UI creations and alterations. It actually lets you open the seperate windows of the UI within the program and move things around and see the xml coding of each piece within the window. I would definately recommend this program for anyone wanting to play around with EQ UI's.