Quick sketch, but should work... if you can understand it. Needs to be an 8 lug 3-way ‘import’, an On/On DPDT mini-switch, and the Neck pup modded to have a separate shield wire. Mini-switch ‘up’ is parallel and ‘down’ is series when in position 2.

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If the sketch is too chaotic to understand I can draw it up properly in the next few days.