You can use a 10K or 20K Goldpoint, DACT, etc. Some require enlarging the hole and/or the anti-rotation hole. Some are too large to fit against the wood base - best to check the dimensions beforehand! The "odd" wiring reduces the switching noise when the contacts get worn, when used in a shunt-mode control as is standard with Foreplay. The shunt mode is preferred sonically by many, and it gives you the option to optimize the gain on each input.
You can use an ordinary volume control potentiometer if you wish, but it will increase the gain by 10dB and may give you hair-trigger volume control - depending on your system components. If you do this, I'd use a 50K or 100K pot.
The PEC pots are well regarded and inexpensive, if you prefer continuous adjustment.
