Once I ripped the 1/4" strips of white ash from the board, I needed them to be more flexible than they were so they wouldn't crack or break when bent in a sharp curve around the mold. To do this, I placed them all in some PVC pipe and attached it to a kettle where water was boiled until steam passed through the pipe. I blocked the openings with rags. Steam was able to escape, but most of it was trapped inside the pipe with the strips of ash, softening them enough to bend them.
With the wood steamed, I mixed some epoxy and glued each piece together (3 strips for the inner and 3 strips for the outer on each end of the canoe). Wood glue would be fine to use here since the stems will be sheathed in fiberglass when finished, so some may consider epoxy to be overkill. Once both inner and outer stem pieces are glued together, clamp both (one on top of the other) to the mold, but DO NOT glue one to the other, they need to be separate pieces (inner and outer). The one closest to the mold becomes the inner and the one on top of that one becomes the outer stem. They must match up, or nest together perfectly, so clamp them together.