sure. just about any 3 band EQ preamp can have 5 pots (volume-volume[blend]-treble-mids-bass). the slap switch I am not so sure about. maybe you can find happiness with a mid frequency selector or an active/passive switch or a series/parallell switch?
actually, the seymour duncan 3 band preamp has a "slap" switch.
thats beyond me i am afraid. I am merely a tinkerer that can read a schematic and solder!
I would start with older active preamp schematics. I found a few pre ernieball MM preamp schematics online. maybe that is a good jumping point for you.