Netatalk is not a jailbroken app.
It's possible, yes. But you will not be able to get any more app updates. There are alternatives to Cydia. You can install Icy if you think Cydia is too bulky, I don't. You can also install APT and SSH so you can do all your app management over commandline from your computer or with MobileTerminal.
Personally... I think you should just install Cydia, I'm not sure why you wouldn't.
Although if you have any Linux experience I think you'd be just fine installing APT and SSH and going that route to keep Cydia off.