I picked up a newer EPA Certified wood stove with the secondary burn for cheap. I also got one for free that was made in 1985 and plan on converting it to a secondary burn stove. It looks very straight forward to do after you look at one that has been done already.
I have some pictures of the secondary burn tubes, but I am unable to resize the pictures without distorting the images.
At the back of my stove and on the bottom, there is a hole on each corner where it goes into a upside down "L" shaped tube inside the stove. That supplies the fresh and highly heated air to the secondary burn chamber on the top of the stove. Thats where you see the tubes with holes in them. There is a really good Youtube video explaining it.
On the front of the stove there is a fresh air intake and it controls the fresh air that goes in and down across the glass. You can see that in the picture I uploaded below.