ECCPM mounts the servo pushrods to the swashplate similar to a equalateral triangle. Three servo's allows the swashplate to be tilted.

Your mixing is done electronically, so will need a radio to support the function like 120 degree is one of the most popular. Not all radios supports this, so look specifically when deciding on a radio that does offer support for this set-up.

You will need 3 servos (same model servos) that have the same torque-transit speed so the torque & speed will match each others movement timing. Some reccomend using digital servos, but I have used digitals-non digitals with good results.