There is a tutorial on nIR photography in this month’s edition of Digital Photo Magazine.
It’s not bad.

In my experience shutter speeds are between 20 secs on a good sunny day to two minutes on a not so good day.

http://www.airplane-pictures.net/image4546.html
http://www.airplane-pictures.net/image2911.html
http://www.airplane-pictures.net/image4536.html

The technique really works well with organic material but falls flat with inorganic aircraft.