Splices for horn bows were always done by hand with a sort of wide bladed hand saw...at least that is what I've seen. There is an older video on youtube for horn bow making (it is done by two amazing American bowers, but I've forgotten their names) that is very comprehensive and he does all the splicing with a hand saw....and does a dang good job of it too. You can always steam the cut for around 20 minutes and then tightly bind it up with a c-clamp or the such for a few days. This will make them fit perfectly if you botched the cut a bit. I often just use a V-splice myself and there is no reason you couldn't do this by hand. Just PRACTICE ON JUNK WOOD FIRST! Also, if you choose to steam clamp, be sure to check the centre line of the bow before setting it out to dry! A lot of times a small mix up during cutting will lead to the bow being misaligned. Luckily, if you are steaming it, you can bend it straight again and then once dried, it will be good to go. You could also use a guide like a piece of hardwood clamped to the limb to align your cuts if you aren't confident in your skills with a saw. I'm no master bower or carpenter and I certainly can't find (in Taiwan where I live) or afford the fancy tools a lot of bowers have, so I've been learning all the tricks for correcting my mistakes ;-). Lastly, USE THE RIGHT GLUE! If you don't know, find out.