Jeff,
Flush kits contain a "tee" which is inserted in one of the heater hoses. I
find it handy way to drain the system.

Pinch off a heater hose in two places, about a foot apart, somewhere
convenient near the middle of the van.  Cut the hose and insert the tee. I
attach a garden hose to direct the discharge to a five gallon container
for inspection, minimize spillage and proper disposal. You can also tell
how much was removed.

Open the bleeder and heater valves and un-pinch the hose.

Repeat every two years. I use Prestone's orange stuff. 280,000 miles on
this engine.

On a separate note; I am NOT a proponent of back flushing the Vanagon
cooling systems. YMMV.
--
Ken Lewis
http://neksiwel.20m.com/