Drawing wavy line across the bars

[Dmitry]

Hi,

Attached is an excerpt from the famous jazz arrangement book by Georgy Garanian.

(In fact, I can't name any other jazz arrangement book in Russian that would be that profound and complete; needless to say, the terminology and notation introduced in the book is widely accepted here in Russia.)

What I'm interested in is that wavy line that comes across the bars (or sometimes between the staves), usually preceded by some text with a \whiteout-like effect. The meaning of this symbol is, "play exactly what other instrument plays". How can I reproduce the same in Lilypond?

From what I've learned yet, I'll have to create an engraver (in Scheme) that should create a spanner (as the object could span several bars). Additionally, I guess we already have some graphical primitive for wavy line, used in glissandos and trills. But it's a bit obscure for me how to bind the things together. I'm a bit new to extending Lilypond, so I'll be grateful if someone experienced gives an outline of the solution.

Thanks in advance!

Dmitry