when hacking at ZBar, PLEASE send patches against the latest Mercurial!
if you haven't already, grab the ZBar Mercurial repository by running:

    hg clone http://zbar.hg.sourceforge.net:8000/hgroot/zbar
    cd zbar
    autoreconf --install

this will generate configure and all that other foo you usually get with
a release.  you will need to have recent versions of some basic "developer
tools" installed in order for this to work, particularly GNU autotools.
these versions of autotools are known to work (newer versions should also
be fine):
    GNU autoconf 2.61
    GNU automake 1.10.1
    GNU libtool 2.2.6
    GNU gettext 0.18.1.1
    GNU pkg-config 0.25
    xmlto 0.0.20-5 (for docs building)
all above mentioned tools (except xmlto) must be installed in the same
prefix. mixing prefixes (i.g. /usr/bin and /usr/local/bin) may lead to
errors in configuration stages

when you're done hacking and want to make your patch, run:

    hg diff --git > hacked.patch

and go post this file in the patches section off the project page:

    http://sourceforge.net/tracker/?group_id=189236&atid=928517

finally, some interesting reading if you want to increase your chances
of patch acceptance:

    http://www.faqs.org/docs/artu/ch19s02.html
    http://www.catb.org/~esr/faqs/smart-questions.html