If I understand your problem correctly. You want to start at the HOME SCREEN, press TRACK button, select a PAD, the fourth knob under the screen is TIME STRETCH, turn it to M. TEMP.
I don’t stretch many samples, i assume the original sample is the same amount of bars for that duration. Play around with it, i think thats the parameter you’re looking for though. TIME STRETCH on the HOME SCREEN.
Hope that helps! I love the Toraiz SP-16! I hope Pioneer continues to development it.