Hi
A good place to start might be to look at the source code of the dBUG application. This is the resident monitor which comes with the Freescale evaluation boards. It would show you how to reprogram the Flash on the MCF5213, and how to bring the chip up and configure a serial port. You'd still need to do a fair amount of work, but it might be a useful resource.
The dBUG source should be downloadable from Freescale's web site.
Hope this helps
Simon