Incipit before ChoirStaff?

[Alexander Kobel]

Hi,

I have a score like this one (in Lilypond 2.10.5)

/
||========|========|==== ...
||
||========|========|==== ...
\

(ChoirStaff and PianoStaff, not shown here) and want to include an
incipit like this:

      /
======||========|========|==== ...
      ||
======||========|========|==== ...
      \

Here's an example in a picture:
http://www.carus-verlag.com/images-intern/medien/30/3500200/3500200n.gif

Using the "ancient notation" template, I can achieve correct
positioning, but how to print a SystemStartBracket (right?) _after_ the
incipit?


Thanks in advance...
Alexander