Well I've been doing update_prebinding from Terminal- seems easy enough: xxxx% update_prebinding -root /

Plus I did it on my Users/3rd-party apps volume: xxxx% update_prebinding -root /Volumes/volumename
That seemed to work fine also- even though the XOptimize help says update_prebinding will only work on /.

I noticed a significant improvement with load time of Canvas, Photoshop, and Painter...(all on /Volumes/Users)