Hi
For low memory footprint KBOOT, Developer's loader (AN2295), UART SREC/IHEX loaders for your parts you can see also
http://www.utasker.com/docs/uTasker/uTaskerSerialLoader.PDF
This will avoid you needing to port or rework code and solves your boot sector protection with a single define:
#define KINETIS_FLASH_CONFIGURATION_PROGRAM_PROTECTION (0xffffffff) // PROT[24:31]:PROT[23:16]:PROT[15:8]:PROT[7:0] - no protection when all are '1'
#define KINETIS_FLASH_CONFIGURATION_PROGRAM_PROTECTION (0xffffffe) for example protects the lowest sector (setting each subsequent bit to 0 protects further sectors).
Works with KDS, CW, IAR, Keil, Rowley Crossworks, Atollic, Green Hills, Coo Cox, GCC and VS.
Kboot UART mode is about 6k (depending on compiler) without any further configuring/optiisation work required. See http://www.utasker.com/kinetis.html for reference binaries available for most boards.
Regards
Mark