Sorry to say, getting a clean output from a Mac without a dedicated video card is impossible.
The ColorSync workflow Mac imposes means all outputs always have a colour profile active, and that cannot be replaced with a 'null/bypass' version.
This is something we have tried to overcome many times, and have never succeeded.
There are other issues too, as some Mac's force YUV output, and cannot use RGB.
There are other discussions on these Mac issue within the forum, as well as within the various website User Guides.
This 11 year old thread should really have been removed, as the information is not valid.
Steve
Steve Shaw
Mob Boss at Light Illusion