Again, it's impossible for the players to support the DM if he doesn't even tell them that he needs support. We've always used the phrase, "Players Police their Own." That means that if the Dm has something he needs done he designates one or all players to do it for him.
Example: We play in Hyboria, the world of Conan. There are no elves. Nothing personal, they just don't exist there. A player comes to the table..late..of course, hasn't read the house-rule-book, and the DM doesn't get a chance to go over his character. Then in the middle of a fight, it turns out that he's playing an elf. I STOPPED THE GAME in the middle of the combat. Noted that I hoped everyone else had read the house rulebook and designated two people to fix this guy's character while I went outside to cool off. Guess how much peer pressure came down on that irresponsible player when 8 players had to sit there and watch him get his character sheet fixed. Needless to say, the rest of the players quickly got the point that if you waste my time, you waste everyone's time. (makes me feel like what our teachers used to say in high school

I put the players to work fixing each other. Peer pressure is a powerful thing.
Other Examples: I run RPGA games and home games so inevitably I always have to face at least one person at the table who knowingly or unknowingly feels it's his job to wreck the game for the DM and everyone else (using whatever the tactic of the day is).
* the domineering guy who tells the other players what to do, it's the guy looking up monsters in the monster manual,
* the guy who blows up and throws his dice at the DM's wife's collectable porcelain dolls when he fails his rolls again,
* the guy who sit's right next to the DM and steals all the action from the other players by talking the DM's ear off,
* the person who added up their stats wrong or obviously cheated on their numbers
* the player who's character always runs away leaving the other people to die, while he goes off and steals the treasure (easily fixed by the DM isn't it?)
* the GIRLFRIEND who keeps telling her husband that he's immature for getting into character
* the guy who keeps getting off topic and talking across the table to another player about his magic game while it's not his turn
* The player who's not paying attention when his turn comes up in combat and we have to wait 30 seconds while he figures out what planet he's on
* the arse that wants to look up every ruling that the DM makes and argue every point
* the guy who knows the world better than the DM and says, "That's not how it is."
* the player who so maximized his barbarian that he makes combats completely no fun for the DM or the other players and then is completely incompetant in all other situations (i.e. basically screws the rest of the party in negotiation circumstances because he doesn't have any other useful skills).
* the drunk guy who picks on another ___player___
* the guy who brings his kid or his dog to the game and thinks that the game always needs to be disrupted because 'they're so cute.' Looooookie, isn' it cute how he just pee'd on the DM's battlemat. Looooookie, isn't he so cute, he just shat on my friend's basement carpet. Loooooookie, isn't he so cute just sitting there barking and whining in his kennel while we're trying to game...
All of those things call for a time out because you can't predict them, but otherwise the'res table rules. Nobody want's to have to be confrontational, but the Dm needs to make the first call. Is he going to deal with it and wreck the game for himself, or is he going to have 5 players gang up on the one jerk at the table. I say, "Make the players help the dm."
jh
..