Creating the eclipse project with cmake as an out-of-source build:
Inside the folder that is used for the out-of-source build (must not be a child of the original source folder) do:
cmake -G "Eclipse CDT4 - Unix Makefiles" \
../../digikam/ <-- your source folder
This creates two eclipse projects. One in the build directory for building and one in the source folder for using Eclipse version control on the sources.