Hey WE b,
Page 39 of the MSD Ignition Wiring Diagrams and Tech Notes book shows how to do it. You can use a MSD 6 box with a Pertronix kit in the following manner:
THE THIN BLACK WIRE FROM THE MSD BOX GOES TO THE NEGATIVE SIDE OF THE COIL
THE ORANGE WIRE GOES TO THE POSITIVE SIDE OF THE COIL.
THE MAGNETIC PICKUP IS NOT USED.
THE HEAVY BLACK WIRE GOES TO THE NEGATIVE SIDE OF THE BATTERY.
THE HEAVY RED WIRE GOES TO THE POSITIVE SIDE OF THE BATTERY.
THE WHITE WIRE FROM THE MSD BOX IS CONNECTED TO THE BLACK WIRE FROM THE PERTRONIX KIT IN THE DISTRIBUTOR.
THE THIN RED WIRE FROM THE MSD BOX IS TAPPED INTO THE RED WIRE THAT GOES BETWEEN THE PERTRONIX KIT TO THE IGNITION SWITCH. BY TAPPED, I MEAN NOT SPLICED, JUST A "T" CONNECTION. THE DISTRIBUTOR TO IGNITION SWITCH CIRCUIT REMAINS INTACT.
I hope that this helps.
