Ah... ya, I don't think that's possible with CT. Sorry.
This is of course one of those "many ways to skin a cat" things so I doubt there's been much demand/need for it.
Personally if it were super important to move backward in time I'd use the Nudge method and clone/archive the original for safe keeping.
Alternatively if you want the "Dial" effect to hear what's up you could nudge the desired clip backward in time MORE than you think you need it to be then apply Channel Tools and use the delay dial to move it "forward" to the point you want.
Pretty much the same thing. Just an extra step.