Jamie,
When I had the problem I first cut a piece of 1/2in? copper tubing and
completly bypassed the rear heater core. (until I could purchase one
$140.00 from the dealer at the time.

My 84 had a bleeder at the top of the rear heater core (white plastic
screw).

Basically I followed bently but started my bleeding process at the rear
heater core first.  It was a bit messy so have some towels on hand.  Then
I worked my way to the radiator.

That's the way I did it; does anyone have a cleaner way to do it?

Dan

97 A4 Quattro
91 Vanagon
74 Beetle
74 Beetle Vert
63 Beetle