its an intel mac
Then you will not be able to run the PPC binary. You have 3 options:
Use a PPC MacOSX machine and follow the OSX instructions.
Use a Windows machine (or boot into windows on your machine) and follow the Windows instructions.
Download the source code from the MacOSX instructions page, extract it, run 'make' and hope that the makefile is x86 clean. If it compiles, you could then run that version on your system. If you get this to work, please upload the x86 binary so that other Intel-Mac owners can use it.