The 24-08 SE layout for 59/09 pickups.
It was requested in the other thread, and I'm adding it here so it can be easily referred to.
The Core 24-08 (or the 35th Anniversary) coil switching is archived with a 3-row switch. It isolates unused coil, and a small value capacitor is added when the given pickup is in split mode.
With 59/09 pickups, we have two issues - 1st is the number of wires coming from the pickup. TCI 85/15 (or 58/15) have five wires, 2 of each for either coil and one chassis ground. The 59/09 only has three wires. The series connection is hooked to one wire running from the pickup. The second issue is the type of mini switches. SE model uses 2PDT mini toggles (2-section switch). Luckily none of these two issues is a massive problem.
The main difference between Core switching and the adopted layout I made is that the unused coil won't be isolated - it will be shut to the ground instead. It will not make a significant tonal change. The 59/09 pickups have always been split that way, and they are highly regarded in full HB mode and split mode.
Looking at my layout, you will see that small-value capacitors and resistors can be used. It's up to the guitar owner what you will go for; they are wired the same way but should NOT be wired together.
Using the resistors, you will archive a partial split used in the McCarty model. There's no difference other than the split can be switched on and off independently to either neck or bridge pickups.
If you go with a capacitor, you will go into a similar approach as Core 24-08. When in split small value capacitor is added to shut a portion of highs to the ground, giving a more polished, less shrill tonality.
Personally - I prefer the resistor split with 59/09
The other mod suggested is to remove the 820k resistor going from the Volume pot lug to the ground (you can clip it off on one side). I needed clarification on why it was used. It's parallel to the outside lugs of a potentiometer how it's wired, decreasing the total resistance of the volume pot from 500k to around 310k. My best bet; PRS tried to reach a happy medium where 500k is best for HB and 250k for single coils. The resistor forces the pot to be somewhere in the middle with the resistance. It's not needed; whatever split configuration you will use, the 59/09 sound great with partial split and the cap mode should take care of spiky splits too.
I would replace the pots, too, but I don't see this as necessary.