An experimental version of guitarix is available for OSX.
Not everything has been tested so far.
It was compiled on Snow Leopard 10.6.8 and has only been tested on 10.6.8 so it might run on other OSX versions and it might not.
It’s available from the files section at https://sourceforge.net/apps/phpbb/guitarix/
JackOSX version 0.89
to run guitarix, start JackOSX (Jackpilot) and then enter into terminal
guitarix -i system:capture_1 -o system:playback_1 system:playback_2
guitarix will probably be a green colour first time starting (emerald skin) so just choose another skin if the green is not to your liking.
if using guitarix with Ardour on OSX, then start guitarix first and then start ardour otherwise there seems to be a problem with some pixmaps or whatever.
Screenshots of guitarix running with ardour 3 and jackosx (jackpilot) and soundflower on Snow Leopard 10.6.8
The guitarix ladspa plugins appear in ardour 3