||01-12-2012 12:56 PM
Not passing code because there are push button switches or switches more than X years old is a separate topic from individual push button switches not passing code or not Underwriters Laboratories listed.
A push button switch will work perfectly well in a grounded metal outlet box. The switch conductors are connected up in the same way as with a modern toggle switch. Special grounding clips that squash between the switch frame (yoke) and the metal box where it is screwed onto can be purchased separately. For plastic boxes, check with your inspector to see whether he will pass a mounting screw, the switch yoke, the special clip, the ground wire from a Romex cable, and the mounting hole in the box all squashed together for an adequate ground.
Another separate topic: Grounding for the branch circuit itself, including grounding of the outlet boxes if metal.