You simply assign a recorder buffer to a flex machine, set the recorder up for sampling from the audio inputs that your source is connected to, put a recorder trig on step 1, but also a play trig on step 1.
Now OT will sample and playback while sampling at the same time, each time it cycles the loop, the recorder buffer will be filled again and played back again. You can´t pitch that up, though, because then the playhead gets in front of the record head (playing back faster) and thus output will result in silence.
You can either delay the playback (hold sample trig and use arrow keys to give it a positive microtming) or you can set a negative microtiming for the recorder trig.
I usually do positive microtiming on the playback.
You can even utilize this technique for shimmer reverbs with OTs dark reverb: