[ubuntu] 13.04 install on mbpro 8,2: black screen

Hi, I downloaded both the 64bit and 64bit+mac version of the iso and used them to boot both from CD and USB (EFI BOOT FROM rEFInd).
I reach to grub2 screen and then is black screen.
If I add some modeset(i915, radeon etc.) to grub2, the same used in the past to switch off video cards and get working framebuffer, I can watch the system loading process trough framebuffer but X fails to start even if I manually load radeon or i915 drivers.
So.. any way to get at least the boot process fully working?

Thanks