The kernel has not been compiled with cifs support. This prevents using the live cd for administration/rescue purposes. Reproducible: Always Steps to Reproduce: 1. 2. 3.
There is SMB support, but without samba on the CD, it isn't very useful, anyway. The same would be true of CIFS support. The installation media is designed for exactly that, installing Gentoo. It is not designed to be a rescue CD and never has been. It is beyond the scope of a Gentoo release.