Good luck with the MC13224 - speaking from experience, I went through the effort of porting FreeRTOS to it. The built-in interrupt handling is painfully slow and creates a bad stackframe, so you either have to work around that and live with the speed, or implement your own IRQ routine and dump 99% of the ROM (the route I ended up taking).
You'll have a tougher time as TinyOS uses nesC and the GCC tool-chain. Not much success has been made with reverse engineering the hardware and ROM, but these guys would be a great start: http://mc1322x.devl.org/. TinyOS looks pretty cool, and it would be nice to have something like Mat'e available for the MC13224, but I have zero familiarity with nes