Here are some trimmers you can use for your wah build that have small knobs on them instead of the screwdriver slot. They're a little more convenient to use than the screwdriver slotted trim pots. They're a bit more expensive so I only replaced the Q trimmer in mine. That and the sweep capacitor switch are the only 2 parameters I ever make changes to so I didn't bother swapping out any of the other trimmers.
Mouser part #'s @ $2.05 a pop
1k - #594-63P102T7
5k - #594-63P502T7
100k - #594-63P104T7
A 100k trimmer will work fine in place of the 250k trimmer in the build instructions.