That's already allowed on player-spawned standard servers.
Originally Posted by 30ROCK
So get a Pro subscription (or switch to your account with Pro subscription, looks like this one is an "alt"), spawn a standard and public server and you get to decide:
- what map pool will be available on post-match voting screen (always current map + 2 from your selected pool),
- whether or not players can vote for maps (this way they can vote for maps that aren't in your pool, but still - only standard maps for current month),
- you can also overrule their votes as the server owner.