Never mind the whole FAA sticker thing, as you are not on a US-based airline, no one will ask.
The sticky bit has to do with whether or not your seat can be attached with only a lap/shoulder belt vs. a lap belt. It's very hard to explain without a diagram. I'll give it a go, but I'll probably be clear as mud, LOL.
For an example of a seat that probably would NOT work on an aircraft, look at
http://www.graco.co.uk/you_your_baby/seat.html
and open up the instructions for the Cosmic. If you look at the directions for mounting it forward-facing with the harness in place, you'll see that the vehicle belt comes up all the way into the "inside" of the seat, just under the padding, then down again on the opposite side. That works fine if the vehicle belt latches far to the side, but remember that aircraft belts are meant to buckle in the centre; the buckle would be a lump right under the baby's bum. (Actually, it would almost surely end up somewhat off-centre, as only one side of the aircraft seat belt adjusts, and it is sized for an average adult.)
Most US-made seats have a channel for the belt to pass through which is *outside* the seating area of the seat; the belt passes under the hard plastic shell, not over part of it. When that is the design, the belt's buckle can still sit near the middle of the seat and it will not matter, because it does not project into the "inside" of the seat, where the baby will be. Most of the time with an American seat, you can open the seatbelt adjustment (on the plane's belt) all the way to the maximum, thread it through the openings, then squish down the childseat and pull on the soft end of the plane seat belt to tighten it; the seat belt buckle will usually almost disappear behind the child seat when it is tightened up all the way. (You might need small hands to reach in there and get it loose at the end of the flight! A good trick is to wait until the people behind you leave, then go around and reach up the junction between the aircraft seat cushion and the backrest, to slip the buckle from that angle. It's easier.)
I sure hope that makes sense; I tried to find a good diagram of a traditional American-style seat installation online, but I couldn't find one, as all of the new seats are using ISOFIX "LATCH" belts, and again, we don't want to go there, because planes don't use that standard.