I think they should be high sec mods only, meaning you have to have a high reputation with your chosen empire to set them up and the empire of choice should dictate the type of operations available (liberate/enslave). That would mean that the empires endorse these actions by pod pilots.
I would not like to see them 0.0 sov claim 1-2-3 etc mods. That will suck. Anyway now we know it is coming we can pester CCP for our wishes on this.
I have ideas on propper transport past customs as well so we can bring slaves into the high sec POS that would be nice for them to add. It involves the use of travle permits (like starbase charters from the LP store, but standings dependent on usage too) allowing for travle within any 0.5 - 1.0 solarsystem without being harrased by customs. They would delete from the cargo when you leave a high sec system. Or maybe they would delete with every encounter with customs drones. Meaning you would have to view your route and the potential for customs encounters (one on either side of a gate).
I am going to put these ideas up when I get the chance and I might incorporate the pos structures into them when I think them through and see what CCP have to say about it. Also if they are not going to be for a while then anyone going to the fanfest should get into the POS and RP roundtable sessions if they have them and pester the Devs about it to make sure they don't half bake this one.