You might want to look into my pitchshifters. I think one of those would be able to do this (if I'm correct, there was one with independent stretch, pitchshift, windowsize, feedback and a ratio that sets the positive/negative division based on the main pitch->inverting this one will cause reverse play-back) The factotum was more meant like a looper instead of a delaymangler.
I also still have some ideas in the work that use external modules (kinda like inserts) to alter the audio in a delay-buffer (eg. adding a diffusion, filter, grain, stretch or shimmer/pitchshift (or whatever effect anyone would create as an insert module, as insert modules could be rewritten with other functionality and added to the available inserts) with each repetition through the delaybuffer). These are still a bit fragmented and not yet all usable together, but the idea is to have a base delay buffer that could act as a looper, grainer or delay and then several external modules that could be put either before, inside the delay-loop or after it. Then the user can choose what kind of functions he would like to perform pre/on/post the buffer by using different insert modules.