Hi there and welcome here.search.php?keywords=appleviewtopic.php?f=57&t=9864&p=57825&hilit=apple#p57825
This last one could work see last message.
Have a look at some links here as well as this is gentoo based and their fixes should work here as well.
Hope something here helps.
You can also try the cheat codes in the readme file on the dvd /.iso you have of Sabayon and several like them. Just search using the top right search /advanced search or even the wiki for cheat codes.
I sometimes boot the dvd by pressing F5 for the text / place to neter the cheat codes and add " xdriver=nvidia res=1440x900 " as this can help or even you might need to add "dodmraid"
Not sure. Some of the guys here owning Apples are likely working on guides for the wiki to help other Apple users.