Calling all PSR Keyboard Experts!

Please help. On the PSR2000:

I'm able to select a built-in 'accompaniment style' and then easily MUTE any individual instrument(s) in that style, but HOW can I change the volume level (up/down) of individual instruments (drums, bass, piano, etc) in a style?

There are a number of internal 'accompaniment styles' where I want to tweak the volume level of individual parts and then save these settings to Registration Memory. Is this possible on the PSR2000? I looked thru the manual and could not find anything on this. Am I missing something here, because the Technics KN5000 easily allows you to easily (on the fly), re-adjust the volume level of indivdual instruments in a style when playing it.

Thanks in advance, - Scott