My cats are indoor-only, and I have never tried to set up any type of cat
fencing.  However, I collected a few links to pictures that show a variety
of methods (some expensive and some completely do-it-yourself).  Here is
what I have in my files:

Design for do-it-yourself barrier to mount on top of fence (to keep cats
in):
http://www.lisaviolet.com/cathouse/backyard.html

Outdoor fence enclosure (several views):
http://www.just4cats.com/
http://www.just4cats.com/post1.html
http://www.just4cats.com/page7.html

A guide to inexpensive do-it-yourself fencing:
http://www.feralcat.com/fence.html

Cat fence-in containment system:
http://www.catfencein.com/
http://www.fabcats.org (includes an information sheet that can be
downloaded)

"Friendly Fence": web site says it is virtually invisible
www.friendlyfence.com

I hope some of this is helpful.

MaryL