Hi
See http://www.utasker.com/kinetis/FRDM-K22F.html
and http://www.utasker.com/docs/uTasker/uTaskerSerialLoader.PDF
Supports UART and/or LPUART - just set
#define LOADER_UART 3 to use the K22's LPUART (UART counting described in http://www.utasker.com/kinetis/UART_LPUART.html)
Works with KDS, CW, IAR, Keil, Rowley Crossworks, Atollic, Green Hills, Coo Cox, GCC and VS.
Kboot UART mode is about 7k (depending on compiler) and supports any available UART/LPUARTs in interrupt or DMA driven modes. Fully set up so you can have a complete, proven solution operating and tested by this evening if required.
See http://www.utasker.com/kinetis.html for reference binaries available for most boards.
This would avoid any need for extra development/porting/optimisation for your project and can be used in the future on almost any Kinetis parts without any extra effort (including mixing with SD card, memory-stick, USB-MSD loaders etc.).
Regards
Mark