Support Plugin - assigning tickets to non admin users

I have a user role called Sysops for community managers. I need to be able to assign tickets to them as well as to Administrators. How can I add Sysop role members to the drop-down for users to assign tickets to?

I am comfortable hacking PHP but I'm concerned that it will break next time I update. Is there an "official" way I could do it?

Thanks in advance,
Mark.

p.s. Support Access is granted.