Yes, it will work. We did similar mod with Marvel once, for testing purposes with C2 Structure cap. It works similar to spdt/dpdt switch, but You have more options.
Not anymore. Marvel is busy making his own amps, lots of orders on bench now.
But the mod isn't anything special actually, if You're familiar with solder iron You may make it for Yourself. You don't even need a board for the mod, You may simply solder resistors paralleled by a caps directly to the spdt switch, then connect opposite sides together, solder wires and voila .
When I'll return home I'll post a few pics of mods done this way.