I just did this on a bow for my brother. Check the bow section for some pics. I've seen others split the tail and use half on the top and the other on the bottom, but I couldn't split a tail for the life of me! So, I just used full tails on each end. The way I did it was separate the twist a bit and insert the base end and pull through to the tip, then wrap the tail tightly around the string until there is about two inches left and stick it through the string again. Repeat on the other limb with another tail. You may have to twist the string again a little bit to snug it up, but once the bow is braced, it will secure the tails nice and tight. They work great. Let them dry and harden and trim the bases of the tails close to the string and you'll be good to go!
FF