Go to the directory C:\Program Files\Metrowerks\CodeWarrior\Freescale_Documentation\pdf\800. In there you'll find a document, 8xx_Bootloader.pdf, which describes how to build a serial bootloader program. This program downloads S1 records to the target processor. The source for the bootloader is in a zip archive file located in the same directory, and you'd use CodeWarrior itself to build it. This should get you started.
---Tom