I've travelled to a lot of different countries and vaping is almost always a big non-event at security.
* treat e-liquid just like any other liquid in your carry-on. I put a back-up supply in my shaving case with my checked luggage, if I have any.
* keep your batteries (all of them) with you in your carry-on, and note any limit restrictions your carrier might have (some, for example allow only 2 extras). Make sure they are not loose (i.e., put them in a plastic carrying case). It's fine to have one in your mod (just like it's fine to have one in your camera).
* I put the mod in my carry-on bag with a bottle in it.
* take a print-out from Rob's web page with you. I've used that to educate some security people (in Europe, for example).
* I travel with the bottle no more than half full on a plane - the lowered pressurization of the cabin at altitude can cause autosquonking with a full bottle.
They see a lot in their jobs and are much more informed than the average guy on the street. Even if one isn't sure, chances are they'll call others over and someone will get it. Remember, you're doing nothing wrong and their only concern is safety on the plane (as opposed to, say, taxation or regulation).