-Can I vent them to atmosphere?
-Is this no-no subject matter?
-will I throw codes?

I'm hooking up this new intake soon and I hate how much oil gets sucked in. Also cuts the issue of plumbing a plastic intake for the breathers. I'm guessing if I just put the little filter guys on there they wouldn't leak oil without the vacuum from the intake. If this pertains to emissions and somehow violates CF rules, sorry in advance.

 

I think you would be OK venting to atmo from the crank case (not sure about legality).

A catch-can is a good investment for any vehicle, especially something like an XJ with higher miles and increased blow-by;