Hi,
If all else fails, try connecting the power phase as you have before but connect the cap to the hot power phase lead and to one of the other phases. If the cap is used as a phase shifter for this particular motor then some combination like this will work, and probably a few different combos for different speeds.
If the cap is used as a capacitor start, there should be a centrifugal switch somewhere, or at least some motors do it this way.
You're going to have to be very careful though just in case anything goes wrong. Safety glasses, etc.
Stand back when you flip the power switch.
Do you have the original power switch for this fan too or not?