I have Bugzilla installed on Ubuntu Server. Is that possible to add syntax highlight to Bugzilla comments (for C++ code)? Now code pasted in comments looks not well formatted and it makes harder to understand it.
No, unfortunately that's not yet implemented, though people have asked for it:
An alternative might be to put a code highlighting tool into your browser. There are at least tow Firefox add-ons which do that:
They let you select code in a web page and display it with highlighting.