mac geekery

Answer

You don’t, really. I mean, in as far as what Apple’s provided to you, you don’t.

However, that hasn’t stopped the crafty AppleScript/CLI crowd from doing silly things to get it done. According to Mac Scripter, there’s a set of AppleScript commands for Mac OS 9 called Jon’s Commands that lets you perform this task in AppleScript. Good news for the two of you reading that are using Mac OS 9, I’d say.

For the rest of you, they link to a nifty tool to do this on the command line. However, the author of the tool has disappeared. Some folks have kept the binary around (it’s freeware) and are hosting it themselves. Using said tool, just issue something like:

./cscreen -x 1024 -y 768