Yes, I'm on the latest stuff - KF5 QT5. To get it working again was a bit of a struggle and definitely confusing. I had to use the kde and qt overlays. There's some details on the gentoo wiki about setting them up (especially the KDE/Overlay page). Once that was in place, I think the rest of the build went ok.

I can extract specific versions, masks, etc if you want, just let me know.

Good to know but I will try it by myself as far as possible. Currently struggling with some package blocks but it seems solvable.

man this is pain in the ***. I still wasn't successfull. After messing up my kde-frameworks-live for 2 days I removed everything and will start over now. lazjen what did you emerge?
or
or did you compile all from sources?

[edit] and did you a clean kde4 free install or do you had an existing kde4 before?

I did the kde-frameworks-live (after trying kde-frameworks) and because this was an existing system that was running the older kstars, it had kde4 in place.

I've also got kde-plasma-live unmasked as well, but I can't remember if that was 100% necessary.

Ok thank you, things can be so easy. And this KF5 Overlay Wiki seems to be quite outdated...
still compiling...

[edit] ... successfully finished. Kf5 and kstars&indlib works
[2nd edit] just for completeness: you dont need "@kde-next-live" for kstars, "@kde-frameworks-live" & "qtmultimedia" should be enough if you dont use the kde desktop itself. This should safe some space if needed.