Thanks to BILL's  answer:

> I had a glass shop do mine and they used a special tool which slides the
> plastic chrome colored trim into the window molding.

I learned that a tool could be used to slip the trim in place. Unfortunately
everyone informed me that the window had to be removed before the trim could be
inserted.

> The only way to install it is to remove your windshield.

NOT!  Armed with the ability to swear #*$%!etc. continuously for two minutes
without repeating myself, I tackled the job with my own homemade tool. Two
hours later the deed is done and a handsome professional looking job it is,
even if I do say so myself.

> I helped the guy install the plastic trim, and with that "special" tool, it
> went in easy--also used some
> soapy water. You can do it by hand if you have the time, but the windshield
> has to be out of the van in order to open the groove.

I used straight liquid dish soap and my crude homemade tool which was one of
the two metal loops, from a paper clamp, held in pair of pliers:
   _
  /  \
  \  /
   | |
_/  \_

I passed the trim through the loop and inserted the loop in the rubber trim
notch. By wiggling and twisting I was able to open the notch enough to slip the
trim in place. By continuously moving the loop along the notch I was able
(eventually) to fit the entire trim strip.

Ain't this fun?
Larry and Fritz our '86 Syncro Westfalia