Yes, the bugzilla is the right place.
If the package isn't available in portage you should also ask for it to be added to the Sabayon overlay.
The procedure to request a package bump or addition is the following:
Select file a Bug →
Login using forum account credentials →
Select Entropy as product →
Select Request as category →
Submit the bug report, if possible describe what the package would do and why it would be a good idea to have it, also specify anything useful to know about it (and about compiling it, USE flags, possible issues, et cetera).