Hi George! Welcome!
You can absolutely use the seam allowances for bone channels! Just press them open and stitch them down. You may have trouble with twisting if you use straight steel boning and your seams are very curvy - it shouldn't twist on the body, but it might lay funny when not in use.
Now (obviously) that will only give you boning on the seams. If you wanted boning in the center of the pieces, you would need to apply bone casing or use a two-layer construction where you could insert boning between the layers, in stitched channels.
