After trying very hard on setting up palm development on windows cygwin environment, but fail. Finally I get it running on OS X environment.
You need the prc-tools to compile the palmos program, prc-tools are just gcc cross-compiler for palmos platform, sometimes we just name it as toolchain. prc-tools is available in sourceforge, but there is no os x binaries download. I found some download link for prctools-osx, but is not valid anymore.
Finally I get a copy of prc-tools from here (it doesn't look like an apple site?), package by Zenonez.com, it should be available in Apple ADC too. According to the announcement, Metrowerks has drop m68k palm support in CodeWarrior, so Zenonez.com continue working on the prc-tools on os x.
Zenonez.com has package everything (including the Palm SDK) together, integrated well with Xcode (OS X Development Tools). I follow the instruction from Zenonez.com to compile MacPalm hello world program, it works. But I can't locate where is the m68k-palmos-gcc compiler. Is 3am after I finish, I should have gone to sleep 2 hours ago.