Thanks Lincolnlov...
my manual is different but I'm sure the instruction is in there someplace.
I'm still deciding where, how and if to cut any holes. I don't want road noise etc. Removed some interior paneling looking for good spots.
I think the best place to cut a vent is in the door jam, like so many cars have vents in the jams. The jam is outside the door gasket and can draw fresh air.
A very short connecting tube and fan could be installed in the rear passenger sidewall paneling without being too obtrusive. But keeping rain out (with a rubber flap?) and similar concerns means I'm mulling it over..
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Meanwhile, one of the places I looked for good opportunity was the rear seat heater / AC vent which goes through the floor console.
Removed the console.
While doing that, fixed the gear shifter "accordion" cover plate thingies.. They were filthy and not operating correctly. Took photos of that internal assembly.... if anyone is curious about how it works and what went wrong.
The moving plates are just a stack of thin vinyl plastic pieces with 90-degree tangs bent up on both ends of the holes. Many were broken off. New plates can be cut with scissors or the old might be repaired.
The assembly is "heat staked" together. Many stakes were broken.... A soldering iron can easily tack-weld things back together.
A higher resolution photo is here:
http://i.imgur.com/3wmsBee.jpg