The front area of the seat pan has integral steps. On my plane I misinterpreted that detail and cut the seat pan so that the steps are separate pieces. (EDIT - the steps are supposed to be separate, see other postings below, so I accidentally got it right!)
This is the area on Dwg 24 that shows this.
The drawing indicates that the spar bulkhead flange goes from side to side. It doesn't, at least on the RV-3B. Here's that area on my plane. The photo was taken prior to adding the steps.
On both pictures, forward is to the left and top is the right side of the plane.
Incidentally, the rudder cable runs directly over the forward outboard screw on the steps. Bit of a pain there.
Just something to be aware of so that you don't need separate parts for the steps.