Have used Chris Gannon's scrub timeline in the past but this is just in another league.
Gonna be so useful I've got a game to debug and am gonna use this which will be fun.
Oh, absolutely. If I understand you correctly, you can already do that. Simply define it as the "animation", like:
var tl = new TimelineLite();
Is that what you mean?
GSDevTools doesn't need to be just wired up to the root/global timeline at all. You can point it at any animation (tween, timeline, whatever). Does that help?