If you have newer version of watch/AP with working RFBSL, it is easy to do development fully on Linux:
* Chronos CC (to flash txt files to watch)
* mspgcc - I used debootstrap to generate unstable chroot, then unpacked binaries from http://losinggeneration.homelinux.org/wp-upload/msp430/ . I had to use apt-get to install one more library, but that was easy.
(Improvements to this "HOWTO" welcome :-).