Do you mean the e-channel stuff like this: 4 Foot Plastic Sliding Door Track - Rockler Woodworking Tools ?

If so, I found that link through this thread that has more suggestions for you Americans: http://www.dendroboard.com/forum/par...e-channel.html

I had a hard time finding the same stuff in Canada. All my local hardware stores denied having it, including the Home Hardware that I found it in.