Apologies for resurrecting this thread, but …
Still there’s no parameter for loop length on AR like on DT but reading on timestretching techniques with velocity mods I had an idea which would probably working.
If you can map sample start, you can map sample end relative to it, too. Let’s say 15 units apart from each other for sake of easiness. And you want 8 slices. But how… do I reliable set velocity to modulate sample start and end in steps of 15 units in order to slice the beat up nicely? Any idea how the 127 velocity steps can be mapped to 120?
calling @sezare56 for help, if you don’t mind… 
First steps can be heard over here:
Edit:
Found another post that more or less did the same – will explore further