i assume you've been trying to install them the same way you would for windows. because that thread only has a small section on installing for mac, i'll quote that section here for ease.
Quote:
It would be nice if you updated the thread with mac installation...
1. Right click on Cortex Command application
2. Click "Explore Directory"/"Resources"/etc.
3. Move mod.rte to opened folder
4. Play
basically, extract it to the resources directory rather than "C:\Program Files\Data Realms\Cortex Command\"
please note you need to extract the mod for it to work. stuffit should expand any mod archive happily.