rolandg,
This is done via external software on your mac/pc (software available at
www.ketron.it - Software - DJ Loop Compiler).
Using the software is easy. Select the part (e.g. Arr A) and then select (on the right) the wave file (from any source ...) you want to associate with Arr A. Repeat for Arr B. Arr C. ..etc/. When done, save the new DJ-Loop.
Connect your Midijay to your mac/pc and copy this new DJ file into the SFX or DJ Loop folder of the Midijay - where the other loops are located.
Thanks,
AJ