I don't think you can get root access to cassini since it's a wikimedia box, they want to keep root access as restricted as possible. You could test it locally of course and submit something that works:)Who is they? Brion? or who? People who handle things like OTRS are well trusted.
In case of cassini, it's both WMDE and the WMF, since it's a toolserver box. The problem is that root access to a toolserver box implies access to *all* data in the wiki databases, including user email, password hashes, etc. That is much more than what OTRS folks get to see.
Ironically, root access to the *production* OSM boxes isn't that critical, because all you can break there is, well, OSM.
Anyway, you might be able to get tooserver root access if you really need it, but as long as you can do without, that would be preferred. Getting you a superuser account on postgres shouldn't be a problem, that's up to Avar.