The way I did it ( and for the record, I can beat 3cai's on ccr aka the ccr macro challenge)
Win 1v1 on titan duel in <10 min
Pick any com (not battle not siege) and lveh fac, build 2 first mexes, 3 solars and a defender/lotus, then move forward while capping mexes and putting at least one solar next to them, sometimes llt (also, put com on high prio). Meanwhile make two darts for scouting, then repeat 3 scorchers+ 1 mason. Scout from two angles with darts, try to keep them alive. Try to kill windgens and close solars, then prevent defense from going up and kill mexes. Try to get ykur scorchers in there asap. With the scorchers, try to kill all builders and eco. If the com is weak (no riot gun, not battle or strike) try to dive it with scorchers, otherwise retreat. Try to get your first mason to expand to one side, put a solar next to each mex, and sometimes a lotus. Second mason should build some sars in the base, then caretaker, llt, solars, caretaker, fusion, caretakers...
When scorchers get less effective, which is soon, repeat 1 leveler + 2/3 ravager + 1mason.
Next match, try to do the same, but give the cai a chance by not raiding it to hard in the first 2mins, focus more on eco and defending with your scorchers.
If this gets easy, try to do the same on other maps and/or two cai's.
Finally move to ccr against 3 cai's or even the ccr macro challenge. By this time you should have 1800-2000 elo.
