A lage cap HEI is actually 3 on the plug going to the module and 2 on the outside row to the vehicle's wiring harness.
I suggest you look at how a stock coil hooks up as your starting point. You'll see that both of the power leads to the coil share a connection to 2 of the wires going down to the module (the third is the ground connection to the module which I doubt you'll be using with a remote-mount canister-style coil).
As you look straight on at the square part of the cap where the connections are I'll see if I can describe the connections....
Along the back row of connections left-to-right (to the module):
Coil to module '-' connection, coil ground, coil to module '+' connection
The front 2 connections left-to0-right (to the stock wiring harness):
TACH connection, 12V+ connection
The TACH and coil to module '-' connections are directly linked to eachother and to the stock coil's '-' side wire (they all share a common connection on a stock coil's '-' side lead)
The 12V+ and coil to module '+' connections are also directly linked to eachother and to the stock coil's '+' side wire (they all share a common connection on the stock coil's '+' side lead).
You are going to have to electrically duplicate this somehow with your external coil. I can think of several ways to do this, some cleaner than others. For sure, somewhere, you'll have 2 wires going to the same connection points since they are shared with both the module and the vehicle's wiring harness connections. Using the terminals on the coil itself would probably be the easiest place to do this rather than trying to use the (now largely useless) terminals in the stock distributor cap. | 
