How Do I change the Android´s default font configuration?

How do i change the android´s system font configuration? O know that it´s a kind of开发者_StackOverflow low level configuration, but i´m not sure where it is located. The idea is to make an option to set the default size, for those with vision disabilities. I need something changeable, not hard coded.

Additional Information: -I will generate a build of the System, so would be no problem changing any system file, class, or anything necessary. -SDK 2.2 - Froyo - API Level 8

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While this is indeed a low-level config change, it isn't really that simple. First, you need to have a rooted device with BusyBox installed. XDA developers made an app (search Type Fresh in the market) that changes the default font for you. I don't believe there's an easy way to do it manually, and AFAIK it's impossible without root and busybox.