Wakeup alarm works pretty much like the alarm function of a mobile phone. Once you have programmed the wakeup time, you can put your Pandora into sleep mode, and it will automatically power on to wake you up. In order to have the actual alarm signal (a media file of your choice), you need to have mplayer on your system which I believe is installed with the community codec pack.

Although I have tried to implement a reasonably friendly interface, there are no plans to burden this app with features. Instead, I hope to see wake-up from sleep mode in other clock apps, notably PandoraClock.

Alarm date and time is accepted in the format of 'date' utility. It's pretty intuitive, but you might want to check out 'man date' in case of issues. The only change I have made is when you provide only hours, minutes (and seconds). In this case, the alarm is always set in the future, today or tomorow. For example, if you set the alarm to "6:00" at noon, it will be set to next morning. The alarm set to "14:00" will ring in two hours.

It is now possible to use Wakeup alarm without entering the password every time. See http://boards.openpandora.org/topic/15800-smart-sudo-script/