I used to set "initiate_all_edge" on Lucid, using gconf-editor > apps > compiz > plugins > scale > screen0 > options. That way, when I move my mouse to "TopRight", scale is started.
However, I'm not able to do the same in Oneiric. I try with TopRight, BottomRight, TopLeft, BottomLeft, but none works. Other settings in the same schema works OK (I've tried with initiate_all_key, changing it to p, and it works).
Please excuse my English language. I'm Latin.
EDIT: Some feedback.
I've just noted that, if I set "initiate_all_edge" to anything, then sidebar stop working when I move the mouse to left edge. I only can reach it using the "super" key. Maybe it's related.