Hi hgporter
I have seen one or two on the forum, you may want to do a search on this forum.
If I recall they had two running that supported a board that held the router up in place (off the stock) and you would move router from side to side over the the stock to remove just a bit in a pass or two or three or more,they look easy to make and use.
Here's a link or two that may help
http://www.leestyron.com/sled.php http://www.routerforums.com/portable...hlight=planing http://www.shopnotes.com/extras/
Bj