Simultaneously? Not without serious modding.
One function at a time? Not without serious modding.
They're not built to be expression pedals. But the Morley has enough room to allow for some unusual modifications... it might be something that could be transformed into an photoresistor-based expression pedal. I know there's open spaces for additional LEDs and LDRs on any current Morley that isn't a wah/volume combo. And in the old chrome Morley wahs... you've got tons of room.
I'd imagine you could install a second LDR, second LED, and drill a hole for a new jack dedicated only to the expression pedal function. There are cutouts in the design of the pedal that will allow the footpedal to affect multiple LED/LDR pairs; you'll see this often in the Morley Wah/Volume combo pedals, but Morley uses the same stock PCB, footpedal, and chassis parts for all their current models. You'll have plenty of room on the PCB to add new parts directly onto it if you wanted; Morley doesn't use all of it for their circuits.
There are multiple requirements you'd need to meet to get it to work right, but that's the starting point right there, I think. Best of all, you could run both functions simultaneously.
Just to warn you, that was just some brainstorming. My electrical experience is pretty limited.
This thread may be of interest to you. It's regarding a different mod, but still helpful for a starting point:
How Do Morley Wahs/Photoresistors Work?
