Lines to show passing the melody between voice parts

[Alison Watkins and the Hawthorn Family]

I am typesetting barbershop music. When the melody is passed from one 
voice part to another this is usually indicated by a straight line from 
the last melodic note of the part losing the melody to the first melodic 
note of the part aquiring it. Hence when you look at the music you can 
see who has the melody at any time. Is it possible to typeset such 
`melodic passing lines' ( is there a correct technical term for these?) 
in lilypond?

Best Wishes
Ian H