OBERHEIM SYNTH

Hello there!

I'm thinkin' about to add pots for cuttof & resonanse control of CEM3320 on my Oberheim DX..
Anyone did this before?
As i can understand from schemes - resonance control is not wired at all (9) and cuttof (12) is fixed by resistor R412..
Is this real to cut that resistor off and just wire a pot?
Or in case of resonance - wire pot straight to the 9 "leg" of CEM chip?
Since i'm musician, and not expert - tell me if i'm wrong :)
I have seen on youtube mod for DX, where some guy made decay controls for every voice...

here's the links:

MOD ON YOUTUBE
http://www.youtube.com/watch?v=aCxfBKb0iOY

DX SCHEMES (TOM CHANNEL, CEM3320 IN THE LOW RIGHT CORNER):
http://www.electrongate.com/obfiles/dx_proc_5_of_7.jpg

CEM3320 CIRCUIT DIAGRAMM:
http://www.electricdruid.net/images/cem3320/larger/CEM3320LowpassFilter.gif

Thanks in any advance!!

XOR