Install and run inetd (or xinetd) at boot

I’m able to easily install inetd by adding the busybox-extras package but I noticed it doesn’t persist after a reboot. Also, it doesn’t install any init.d script, and my modifications to /etc/services don’t persist either. I’m obviously going at this the wrong way.

Is there any guide on installing packages on HA OS and how init works on that specific OS?