Expression Pedal in Halion Sonic 3


I have a problem: I want to disable the control of Volume by the Expression Pedal.
Standard on all sounds in Halion Sonic the Expression Pedal is assigned to volume, which is very unhandy if I want to control a Filter by my Expression Pedal. I really like the Clavinet sounds and want to program a Wah Wah Pedal effect on it. Is there a way to disable the Volume effect?

Steinberg, if you read this: PLEASE add a switch so we can disable the Expression Pedal to control Volume!
Thank you!