Sorry to open up an old thread but while on sabayon's irc channel today, people were discussing on an alternative frontend to portage instead of Kuroo. They seem to be recommending portato over kuroo.
Check this
http://forums.gentoo.org/viewtopic-t-502350.html
Anyways cli is still the best way. But if you still need a GUI way then go for portato rather than kuroo. Reasons are discussed on their forum check the link above.