How to install and run inetd on OSX or the equivalent in launchd

I'm trying to capture the data destined for a "networked printer" so it can be processed locally or forwarded to another system. It looks like https://unix.stackexchange.com/questions/203173/linux-as-a-network-printer-device-raw-port-9100 will do what I want and only requires: 9100 stream tcp nowait cat > some_file but I'd like to be able to test it on my Macbook and that does not have inetd. Potentially I could use launchd as it is the replacement for inetd on OSX, but reading the docs, it is not clear how to do the equivalent to the above. So either solution--how to get inetd for OSX or how to create a plist file for launchd do that does the equivalent is what I'm looking for.