Michiel,
I have now installed BZ on a SME 6.0.1 server and I installed a few dev. tools to be able to do it. These were needed only to get and update a ton of Perl modules. I am not sure whether they are all nessesary (I am quite sure not) but it was easy

. These are all found on
http://mirror.contribs.org/smeserver/contribs/hpe/devtools-6.01/dev-rpms/autoconf-2.13-17.noarch.rpm
automake-1.4p5-4.noarch.rpm
bison-1.35-1.i386.rpm
cpp-2.96-113.i386.rpm
gcc-2.96-113.i386.rpm
gcc-c++-2.96-113.i386.rpm
gettext-0.11.1-2.i386.rpm
glibc-devel-2.2.5-44.i386.rpm
glibc-kernheaders-2.4-7.16.i386.rpm
kernel-source-2.4.20-18.7.i386.rpm
libacl-2.0.11-7.i386.rpm
libacl-devel-2.0.11-7.i386.rpm
libattr-2.0.8-6.i386.rpm
libstdc++-devel-2.96-113.i386.rpm
m4-1.4.1-7.i386.rpm
mkisofs-1.10-11.i386.rpm
ncurses-devel-5.2-26.i386.rpm
readline-devel-4.2a-4.i386.rpm
Next I updated the CPAN base.
# perl -MCPAN -e 'install Bundle::CPAN'
Then I took all the Perl modules one by one as indicated by Bugzilla installation guide.
Create a ibay called bugzilla and untar'ed a BZ tar file into cgi-bin. Ran ./checksetup.pl to verify all modules were there and create a basis installation. My installation is a little tricky as my mySQL database is on another server.
These are the basics I think.
Enjoy,
Jesper