Nice thread, Susan. Songleading is best accomplished through attitude. I have run workshops on the subject and I have come up with a few general principles. To, effectively, lead singing, one must become a part of the group, willing to surpress his need for applause and attention, willing to pitch the song in a key that the others can reach, willing to, openly, encourage participation, willing to sing those "tired old chestnuts" that everyone knows, willing to slowly and carefully teach the words, repeating them as often as needed.
Songleading means skipping those instrumental breaks that you have been working on so long. Songleading means encouraging blending and harmony. Songleading means making them the stars. Successfull songleading means that no one will notice your great accompaniment. They will, just, notice themselves and the fun they are having. They will applaud, but they are, really, clapping for themselves and that's just swell.
I think that songleading is my favorite way of performing. It's not for everyone, but it suits me fine.

                         Mike