My god I think I finally got it, 5 hours later…
First, the switch pins will connect 2-3,5-6 OR 2-3,5-4 OR 2-1,5-4
Check this continuity on your switch to make sure you have the proper type ON-ON-ON for those positions. I had to wire my switch backwards (left-right) from what’s in the SDE Mod Wiki. If you view the bottom of the switch, the terminals are numbered like this.
So I think the wiring goes like this.
Lift the side of R18 (1k) that goes to GND.
Remove R19 and replace with a straight piece of wire to bridge it.
PIN 6: Connect this pin to diodes then run a wire from the other side of the diodes to IC7 PIN1 (use the top pin of where C32 was if you did the Filter Shape mod)
PIN 5: Bridge a 1k resistor and a 1uf cap across pins 4 and 5. Now run a wire from PIN 5 to a GND source – you can use any nearby ground, for example if you already ran a GND wire to another mod pot / switch.
PIN 4: Now that you have already bridged the 1k resistor and 1uf cap from here to PIN 5, run a wire from PIN 4 to the side of R18 that you lifted (the other side of R18 stays in its original hole which connects to IC3 pin 4).
PIN 3: Connect a wire from here to the “bottom” hole of where C15 used to be (the hole farthest from IC3, and which connects electrically to R16).
PIN 2: Run a wire from here to the “top” hole of where C15 used to be (the hole which connects electrically to IC2 pin 1). Apparently this is where “MIX” in the original diagram goes and it actually corresponds to “MIXOUT” from the Filter Shapes mod. I figured out that this goes to the C15 hole by process of elimination.
PIN 1: Not connected to anything.
I don’t know if this is correct, but it sounds good and gives some hella crazy options when you tweak the resonance. If used in conjunction with the other mods, the 3 switch positions will vary from subtle differences to bigger differences depending on what filter mode you’re in and what filter “flavor” you use.
I hope this helps somebody. The original explanation and accompanying schematic were confusing and contradictory. I will monitor this thread for replies in the future so if anyone needs further explanation I will draw a diagram, just ask.