I can give you a few hints. not home right now:
First you connect the a DialP to posMod IN. You will notice that when you turn up the knob at some point you will reach the end of the file loaded. For me I reach end of audiofile at 4 so I need to make those 4 fill out ALL 128 steps of the dial or fader...... So i calculated 128/4 = 32... 32 was a bit too much so I added a divide by 8.
So: Dial to Divider to pos of the sampler. Then you have position mod. If the division is not perfect you can put in an attenuator or similar to adjust the division amount.
Take a look at the SLICE function of the Amon is Broke tutorial... It shows almost exactly what I described above
Assuming you have audio playing and that part is working.