In OS X there is seemingly no way to set up the computer to start automatically at a given time. This has bothered me for a while, and I've tried to find a way to do it. I even posted a question about it in the forums on this site, and got a few wild and crazy suggestions on how to do it. Since they involved cutting and restoring the power to the power supply, I didn't even bother trying them (those things do horrible things to your drive if you're temporarily out of luck).
There was a way in OS 9, by using the Energy Saver preference panel.
It still works!
Boot in OS 9, set the time in Energy Saver, launch Startup Disk and select OS X. Shut down and relax. Your computer will now boot (in OS X) at the time you set in OS 9. Sheesh...!

