How can I add standard users to the print managers group?
You can grant users partial admin rights (printers only) by making them members of the _lpadmin group.  This is a hidden system group, so it doesn't appear in the Accounts preference pane; you have to grant membership from the command line (as a real admin).  You can do this for an individual user:

sudo dseditgroup -o edit -a fred _lpadmin


or just add everyone:

sudo dseditgroup -o edit -t group -a everyone _lpadmin


BTW, membership in _lpadmin grants both the ability to manage queues, and also configure printer settings; if you just want to grant queue management (e.g. resuming queues), I believe you can do that by adding people to _lpoperator instead.