It was very hard to look for an answer through the forum since almost every thread has some links to SME's bugzilla.
I am looking for a way to install Bugzilla ON SME 7.4.
Anyone might have some experience with that ?
Try the contrib from the atrpms repository (RHEL4 version might install on SME Server 7).
Otherwise you can (just) follow the instructions on the bugzilla wiki to manually install it (
http://www.bugzilla.org/docs/3.4/en/html/installing-bugzilla.html), taking into account that the configuration files for default SME Server services, like Apache/httpd are build from templates. More on that is in the SME Server Developers Guide linked from the wiki.
Some work has been done on a bugzilla contrib (according to the bugzilla and my memory

but a integration RPM was never finished AFAIK).