[Mike]

The information you are seeking is largely answered by the Rotozip template kit mentioned in the next post, well worth the price. View it here: http://www.routerforums.com/36134-post1.html
I bought mine at Lowes a few years ago.
Another style of trivet is worth a look. This one is simply crossed bars that lock together with dovetails.

 

[Mike]

I will try to locate the part number for the template kit. If it is no longer available I have no problem posting a copy of the instructions (which is the important part) here on the forums. This is officialy on my to do list now.