This might help: it's the hardwired version of the EXB. Replace the EXB with the tone pot. The "white" wire going into the EXB, instead of going into the EXB, is "side wired" to the tone control as below and continues on and solders on to the same lug of the jack where the "green" wire coming out of the EXB goes, and the "red" wire coming off the battery terminal only goes upstream to the red pickup wires as in the middle of the page with two volume knobs, one for each pickup.
Now, for the tone control, here is another diagram for one of their older passive models. Use a .1 capacitor and a 25kohm potentiometer, which you can get both from EMG and a variety of other supply houses. http://www.emgpickups.com/content/wi...agrams/MMHZ%20
Hope these help!