use expression pedal for volume and to increase od gain ?

[mantra]

Hi
is there to use the expression pedal for the volume to increase/decrease volume ,and the assign to disable and use the expression pedal to increase the overdrive gain?

I was able to to use the expression pedal to increase the od gain but can I have a preset with the foot pedal to increase/decrease  volume and assign clt pedal to  disable the volume and enable the expression pedal to control the overdrive gain values ?

i have tried with fx floorboard without luck
thanks