One technique is to buy bulk screening and cut it to fit larger than the Xterra window and use magnet strips to hold it to the exterior window frame.

But I ran across this guys idea for his van and thought it wasn't too shabby either.

http://www.cs.rochester.edu/u/jag/vw/angel/jagPRVWdoorSmall.jpg

Kick ass idea. I'll definitely use that next time I sleep in my X. Thanx.

looks like a good first project for the industrial sewing machine my mom just gave me. I even have a roll of screen in the house. :)