You can't. Timeline is the new version of the profile and like with all nearly every service out there, you get to use what's current. All brand pages will be converted over tomorrow, personal pages have already started to be moved.
So let's table the "I don't want it" discussion and talk about why you don't want it... What's your concern?
What's in the Facebook Timeline update that you don't like? Are you having some issues with it? If you have a fan page, I think you should accept the fact that the Timeline is going to be standard for the pages. I remember seeing some sort of a browser fix that would help you make Facebook look like it's using the old layout, but that would only be visible to you. Well, not unless others are using it as well. Search for the how to videos. There are a lot, but I'm not sure which one's is that video that I saw before.
Unfortunately its the new direction that Facebook is going. Try to focus on the positive aspects of the new page, change is never something that is easy to get used to, especially on a site that many people use daily.
I think overall its got some great benefits within a few months everyone will be used to it and loving it.