Simon,

For an expression pedal i've been using a Boss fv500L with a trs cable on the expression output. It works well, thought there's a bit of a dead zone at the toe position.

For a switch pedal, i've been using a Mesa Boogie Recto Pre pedal i had lying around. The left button works (tip2 mapped to pgm+, latching) though the right button doesn't – it just toggles its LED.
I'll probably eventually go with one of thesebthat some of Factor pedal users seem to use successfully.
http://this1smyne.com/shop/e3-eventide-aux-switcher/
http://www.digitech.com/en-US/products/fs3x-3-button-footswitch

I hope that helps.
Cheers,
af