is this http://www.dolphinmusic.co.uk/product/40893-zoom-fp02-expression-pedal.html/?utm_source=google&utm_medium=shopping&utm_campaign=base

essentially just a pot controlled by a pedal? would this http://www.diystompboxes.com/pedals/zoom1.jpg work as a schematic? i have a zoom G1 and a volume pot and im wondering whether i could make the expression pedal with it an make a chasis at my school. advice would be appreciated
My Rig:
American Standard Telecaster
Fender Starcaster
Sp. Edition Jack Daniels Strat (Modded)
Vox AC15CC1

Stuff I've Built:
Telecaster Deluxe
Telecaster Junior
Pedalboard (from a shelf )
the odd pedal