Hi rhiansheehan,
Yes that's easy.
steps :
- move your expression pedal
- press edit
- then press CC
- turn Value knob and choose 1
- press value knob to enter modification
- press edit to leave edit mode.
You've mapped CC1 (modwheel) on expression pedal.
You can do the same with the MidiControlCenter simply by clicking on expression output jack and choose CC1 instead of CC11, then store your changes in the KL memory.