This question of how to hold conquered cities keeps popping up. I'll tell you a few more options that haven't been mentioned:
1) Just let it flip. Empty it out, and have an offensive unit or two next door to retake it just in case.
2) Hello, like, make peace!
3) Still no patch? Sell the city to a third party who gives you Right of Passage. Not sure if that'll work post-patch.
4) If you're gold-rich or still in Despotism, hurry out Workers & Settlers. Don't just waste the population--waste them in a useful manner.

What's a worker--36 gold to hurry?
5) Once the city is stabilized (i.e. no resistance, no disorder, no starvation), train workers the normal way. If you're food-rich, this replaces the foreign nationals with your own citizens. If you're not food-rich, this slowly reduces the population. Either way, it's good. If you're pop 1, train a warrior to garrison.
Also, a few things about garrisons:
1) It seems you MUST have at least as many units as citizens to prevent a flip, when you're in disorder/resistance. I've had flips when I had "almost" enough, but never when I matched or exceeded the citizens. When you bring the city to order, you can slack off a little bit.
2) This is all the more reason to attack the AI with an overwhelming force--not just to minimize casualties, but so you can garrison. If you just have an "edge," you need to wait. Hard as it is.
3) Keep all those old Swordsmen, Hoplites, etc.. They make great garrison units, while your Cavalry goes out and does the fighting.
4) Have any other useless, one-shield, 1-pop cities in your empire? Train up warriors specifically for garrisoning. This suddenly makes those cities useful.
5) Draft. Conscripts garrison beautifully. Another use for useless and/or "Growth in 9999" cities. Just watch your happiness.
6) You'll tend to garrison and heal damaged units at the same time, so if you don't have Sun Tzu, you can hurry a Barracks out, to heal faster. (BTW this is the single biggest selling point for Sun Tzu: you have automatic Barracks even while the city is still resisting.)