If you can find the little protective orange clips that came with the printheads and covered the actual head and ink ports, use them and put everything in zip lock bags. Squeeze as much air out as you can (I would use the submerge method- google zip lock bags and Sous Vide steaks). If you can't find the clips, just use the bags but only put one PH in each bag so the actual heads don't get scratched.
I don't see any point in bagging the ink cartridges since they're pretty well sealed on their own. I've had cartridges sitting around for a year or more, partially used and not at all protected and they've done just fine. Can't hurt, though.
If you really want to be cautious, purge the ink system on the printer. When it's time to put it all back together, you'll have to use a primer syringe (call LPS) or the expensive little primer heads that HP sells. If you're not used to working on the printers, the syringe method might be intimidating but it's childsplay, really.
If you're in the US PM me your address and I'll mail you a set of orange clips if you want. I've got two Z3200s and run a volume business, so I've got a jar full of those things. Happy to do so internationally as well, but I'd appreciate the postage for that.