Building lilypond on osx

[Luca Fascione]

Hi,
I'm setting up to build lilypond on osx and I'm trying to keep tidy notes
so we might add them to the CG once this is all worked out.
At this time I'm using homebrew as the package manager to install
dependencies.

OSX installations come with some of the packages lilypond needs available
as older versions than required, but the system version cannot be changed.
To deal with this, homebrew introduced the concept of keg-only packages,
that are made available only for compilation work
(homebrew likes to build on the user machine if it can).

As I'm working through setting up the parameters to pass to configure I was
wondering what the recommended approach is to tell the current build system
to use (for example) /usr/local/Cellar/bison/3.8.2/bin/bison in lieu of
/usr/bin/bison
(I also need to repoint flex and maybe gettext, gettext is strange)

Thanks for your help
Luca
-- 
Luca Fascione