I've just tried to install alpha3 on kvm myself, and it does indeed fail. The failsafeDexconf -issues are fixed now in git, but the real problem is why it ended up there. It tries to use the cirrus driver, but it fails to configure itself properly. I used the xorg.conf from failsafeDexconf as a base, and it seems to require the modeline, defaultdepth and modes to actually start up. It needs to be fixed in the driver, unless I've misunderstood.
I've just tried to install alpha3 on kvm myself, and it does indeed fail. The failsafeDexconf -issues are fixed now in git, but the real problem is why it ended up there. It tries to use the cirrus driver, but it fails to configure itself properly. I used the xorg.conf from failsafeDexconf as a base, and it seems to require the modeline, defaultdepth and modes to actually start up. It needs to be fixed in the driver, unless I've misunderstood.