Hold the two side buttons when you power the radio up. The default password should be 123456. Make sure your channel selector is set on channel 1. You can cycle through the zones with the side buttons and once you pick the appropriate zone click your channel knob over to channel 2 and you can use the side buttons to pick the channel you want to edit. Channel selection 3 and up are the parameters for the channel you're editing. Pressing the orange button on top will cycle your menu selection from 1-16 to 17-32. I believe the settings should save when you power down the radio, I haven't played with the feature that much.
I'm not sure if this feature is standard. My VX-P829 with the CE106 Talon software and federal firmware is what I've tested this process with.