Reply by Lifesaver2000

It is possible the Wolfcraft Dowel Pro Jig will do what you want, and can at times be picked up for about $19.95 on sale on Rockler or Amazon. I have the jig but have never needed to do what you are saying, but the directions have instructions on how to do it (if I understand what you need to do).

You can read the directions at the link below (PDF file)

http://www.wolfcraft.us/pdf/3751-dowelprokit.pdf

I think they call it a “T-butt joint”