I tie on like Michael described. A trick I learned from Daryl Lancaster,in an excellent Weavolution class, is to start tying on in the middle of the warp. Tie on 1 to 3 sections, then advance the ratchet 2 clicks. Then tie on 1 or 2 sections at each side and advance another 2 clicks. Keep doing this until you reach the edges. If you do this, you don't have to go back and tighten up the knots.
Slippery yarn, as beautiful as it is, is a PIA. One thing that I've done is, after tying on, I further secure the groups by putting a small rubber band around them, or I wrap them with a piece of masking tape. Of course the tape option is problematic if you had plans to use those ends as fringe later on, but it does keep them from slipping and loosening.