Sometimes, Gentoo is just a little "complex"…..
If you add the complexity of the graphical user interfaces you can go crazy, this is just a little tip to activate the NUMLOCK at every boot time. You can do this action simply from the shell avoiding the use of the GUI.
The Gentoo init system uses a dependency-tree to decide what service needs to be started first. Being a tedious task to do manually, it has been added a tool to simplify the administration of the runlevels and init scripts. This tool is the rc-update.
With rc-update you can add and remove init scripts to a runlevel. The rc-update tool automatically queries depscan.sh to rebuild the dependency tree.
Let's go back to our problem, we have to say to rc-update to start the NUMLOCK at boot time:
# rc-update add numlock default && /etc/init.d/numlock start
That's all, since the next startup, the NUMLOCK will be active.