Thread:Project:Support desk/Set the timezone for users who have not selected one in their preferences?

I'm trying to figure out how to set the timezone for users who haven't already selected one in their preferences. I've had no luck using either $wgLocaltimezone or $wgDefaultUserOptions['timecorrection']. All I want is for the "Time zone" preference to be set to "America/New York" for everyone who uses the wiki. Is there any way to do this?