I have written a guide to achieving the above at a 21,5" amd radeon 6770m 2011 imac, it was quite painfull, but the guide hopefuly will make the process less painfull to you if you want to do this dual-boot.
I accept suggestions to improve it; you can redistribute and improve the guide yourself, as long as you mention me as the original author.
At firefox bottom-left area you can see where the linked image redirects you to.
