You already know this, and I know this isn't what you're asking for, but... When you're in the Now Playing screen (the one that's like "now and next" on the Empeg), press the wheel in. You'll get a menu that lets you insert tunes and such. Okay, with that said...

To me, that seems to me to be the proper place to add the tweak order functionality. There's a couple ways you could go about it. You could add a tweak menu to that menu, or (I think one of the Cambridge guys suggested this), when you select "Insert/Artist", it could default to the currently selected artist instead of at the top of the tree.