Hi,
I just do how Incra says in the instructions , a piece of scrap to center then a piece for the depth, then I use that piece for a backing board to eliminate tearout.
I thought the centering jig would save some time/wood but contacted Incra through E-mail and they said they have them but said you get better results from doing the centering cut proceedure so I opted out.
I am going to call them because I was thinking of using one of those centering pins for a router to do it, it seems it would be more accurate than two cuts then eyeballing the center.
Do you have the master template library book and templates? They have the manuals on the Icra site.
I did forget to say that INCRA has the best product support I have ever come across, feel free to call or
E-mail them there great!! They even suggest you call because it is easier to answer questions about their products in person.
Mark
-- MARK IN BOB, So. CAL