Expression Pedal with GA5

hello there!
Here’s the deal. I’ve got Groove Agent 5
and couple of Simon Phillips extensions installed.
GA5 let’s me controll the Hihat open-close parameters gradually
by the modulation wheel by default.
I would like to reassign those parameters
to be controlled by the Expression pedal (CC11).
I’m using Novation Impulse keyboard in Persons Studio One
and there seems to be no way for me to accomplish this inside of those.
Is there a way I can do it inside the Groove Agent?
maybe by using Learn controller or something like that.
I haven’t been able to find it out. Thanks