How do I make an HTML page print in landscape when the user selects 'print'?

We generate web pages that should always be printed in landscape mode. Web browser print dialogs default to portrait, so for every print job the user has to manually select landscape. It's minor, but would be nice for the user if we can remove this unnecessary step.

Thanks in advance to all respondents.

A quick Google indicates that it's not really supported. There's more than a few folks out there trying to hack their way to it - but I'd strongly suggest just rendering a server side PDF instead.