The compiler and open ocd plugin seam to be avalable only for window/linux as of now
you can try to install ac6 toolchain or plugin from update site and then add the missing brick separately
intall an arm gcc from lunchpad or code sourcery .. then configure it in projects
open ocd and gdb h/w debuging plugin should be availble for mac (i did not tried) but i know of mac user using them over different eclispe plugin so it must exist some way
You will loose the ac6 nice feature and ease of lunching configuriong the debug/flash in a singel click.