I've found plenty of descriptions which use pkg-config or else, but none of them was as easy as for Boost or SDL. Is there an easier way like this:
FIND_PACKAGE( SigC++ REQUIRED )
If not what is the best way to use SigC++ with cmake?
No, unless there is a FindSigC++.cmake module. I'd advice you to use pkg-config, because pkg_check_modules (GLIB2 glib-2.0)
is not that much more difficult.