How to turn off sleep when using disk utility or reinstalling?

When I've used the disk utility or reinstalled Mac OSX the screen shuts off after a while because I'm not using the keys or trackpad. I don't want to keep having to move the trackpad so the screen comes back on because the computer would be writing data then. Is there any way to turn sleep or whatever you'd call it off while using the disk utility or reinstalling Mac OSX?

Note: when using my computer normally like I am now this isn't an issue because I have the computer set to not put the monitor to sleep unless there has been three hours without computer use.

under preferences there is energy saver in there are the options i think your looking for. i am pretty new at mac but maybe this will help until someone is around that really knows what they are talking about..

System Preferences ---> Energy Saver ---> Change display and computer to sleep: Never

There are also applications that allow you to do this without going through system preferences. I use Caffeine. For what you are looking for, Caffeine would work good because it is just a simple click to make the display stay on and the computer not to sleep. Check it out: http://download.cnet.com/Caffeine/3000-2094_4-140937.html?tag=mncol
Good Luck