I agree with "dawg" about using the resistor with a pot if you plan you use the pot in place of a trimpot or resistor but what do you do when you don't know what resistor value to use and you don't want a pot there permanetly? Say in the case of the MK2 deciding between the 100k or 47k resistor.
What I'm making now from an old MXR style box where a paint job went horribly bad, is a variable resistance machine by connecting a B1000k, a B100k, and B1k pots in series. This way I can have from 0 to 1101k to play with. You can also think of them as course, medium and fine adjustments too. Say if you wanted to get a 575k resistance get 500k from the B1M pot, and ~75k from the B100k pot, and then dial in the last bit on the B1k to hit 575k exactly. The B1k is also required to get to values under 1k. That's why I chose a 1k instead of a 5k for sub 1k adjustment granularity.
Now add two female banana input plugs to the box so I could attach two male banana plugs from a DVM to it to measure the resistance at the PCB. Then there are two wires that come out another hole that you attach to PCB with a bit of electrical tape to where the resistor is question goes and you can adjust the resistance on the fly while playing. Now you can test virtually any number of values up to 1101k to find your sweet spot then you know exactly what resistor to use.
Yes, somewhat limited usefulness. Yes, you can do this with a breadboard... Have I tried it yet? Nope.
Building it right now. I have the old box, some $2 pots and some time to kill so I'll make it to go with my "Mr. Keen" transistor tester.
Here's a diagram of the variable resistance machine.