It is as simple as putting a file on the root of a SD card and booting up with that in the unit. The only tricky part is navigating through test mode. While i did not find it difficult to learn quickly, i have read through a lot of ppl posting how the deleted something when they didnt mean to, but clicked the wrong button, or something to that affect.
So just be careful, copy the USER folder and paste it to the sd card. go straight to a pc, save that folder somewhere safe. As long as that is your first step you should have no issues, then if you delete the wrong thing you have a back up yo