OK, I found a post that should help you:

1. Set slide switch to selected component.
2. With a ball point pen press "set".
3. Enter a two digit code.
4. Press "enter".

To change the factory preset volume control from one device to another:

1. Set slide switch to selected component.
2. Press "set".
3. To control sound through AV1 press "VOL-". To control sound through AV2 press "MUTE". To control sound through TV press "VOL+".
4. Press "ENTER".
5. Test by pressing vol+/vol-.

I've done a little searching, and it seems the two-digit component codes are the same as those used for the RM-AV2000. Click on Reviews, then select the AV2000, then click on Component Codes. Something there should work.