Can I change the amount of time that the screen will be dimmed to under one minute?

I’m talking about Mac OS X Leopard.

In the Energy Preference-tab, you can change the amount of time until the screen wil be dimmed. It varies from 1 minute to never. Can you change this to under a minute using a Terminal command or something?

I let my Mac play iTunes while I’m sleeping, and I set the dim-time to 1 minute, but I was wondering if you could change it to 5 seconds.

Thanks, Davey.