Also tried SETVAR;TRANSITION;XX
None of these worked and I'm not sure why. I thought anything in rr.ini or skin.ini could be changed on the fly with a variable of the same name.
For example I am pretty sure if you want a different background on each screen can't you SETVAR;BACKGROUND;XX before loading the next screen??? I would think what I tried with the SETVAR;TRANSITION;XX is the same type of thing.