Thanks guys for the compliments on the sinew job....that means alot to me. I have found that laying dry bundle of fibers down onto a wet glued surface, then simultaneously straightening and tamping with thin glue allows me to straighten the bundles and get a good glue set, then pressing firmly with your thumb into the bundle helps smooth things over and pushes out any excess glue.
razorsharptokill, when you work that elk leg sinew, don't try to smash the sinew with a big hammer, rather use a continuous beating, letting the weight of the hammer, or stone, do the work. The tendon should not get warm from the pounding. I have found that you can "plasticize", for lake of a better term, the sinew by pounding it too hard, just use lots of smaller beats. For each minute of pounding, roll the sinew in the palms for a half minute to help separate the fibers.
I think a different design and different wood, might permit adding sinew later in the game without any ill effect. That said, I don't think I would ever sinew a bow already tillered out to target draw length.