If you switch over to another virtual cosole (Ctrl+Alt+F[2-6]) and run the pretend command that PovMan mentioned:
It will show you all the dependencies that haven't finished emerging yet (shift-PgUp/PgDown to scroll). It's nothing all that detailed, but at least it'll give you some idea of where you stand. Unless they've replaced the default KDE install with the split e-builds, there will probably be 20(?)-ish packages that start with kde-base. These are all pretty huge, probably taking a few hours to install each.
I remember I did the very same thing when installing Gentoo on my 850Mhz test laptop for the first time. Let the whole thing just run over the weekend. Took forever, but eventually it finished. Just hang in there. I've never had any problems where portage launched into an infinite loop instead of kicking out an error message and stopping.
Any problem can be solved. You just need to throw enough time and ninjas at it.