1. Research AH first. If you don't have 6 horses in your capital location and a
secure expo location, try an Archer/CB rush instead.
2. Assuming horses, get to work stealing workers as per usual. You CAN'T do a CA rush without worker-stealing. Someone people don't like worker stealing but if you have to build them, it will be too late.
3. Go Liberty. You will need it for the hammers, the fast settler, and later, the happiness and culture.
4. Once you have your workers and your expos, divide your workers between those who chop the forests to make the birch canes to 'train' the CAs (and make the chariots, presumably

); and the second set, who improve the horses themselves. Six workers is perfect.
5. Make one horseman for city capture and train him on barbs if need be to get promotions. He will need to be a little beefier than your average meat-shield. If he dies, replace him immediately. Time wasted with no unit to capture is lethal on Deity.
6. Assault the weakest of the nearby armies and kill all their units in the open before you approach their city. CAs can't stand much of a hit. If the city has a CB you MUST bait him with workers and kill him. If the AI builds another to replace him, again back off until you can actually capture the city.
7. All promotions are instant heal. You will make Knights out of these after T100 so don't bother giving them promotions they won't keep. The heal will help them take out cities quicker.
8. Raze all cities except capitals. They won't have anything good in them worth keeping them for. Don't worry about unhappiness as long as it stays above -10.
9. Press as hard and as fast as you can with crazy numbers of units. Keep 2-3 workers at home to improve your cities to maximise hammers and food. Your cities should grow so you can support many units.
10. When you get to Chivalry, disband all but 3 of your units, sell the surplus horses and build XBs instead. It is also useful if you build archers/CBs and train them on a city state then upgrade them.