What is the "aux contact" for? Is it to supply power to the motor from multiple sources? Is it a output from a sensor on or driven by the motor? What type of motor are you talking about? Much more information is needed...
An aux contact usually applies to an extra contact on a motor controller/contactor etc, this would be used for several purposes, usually as an interlock or a retaining contact across a P.B. etc.
In the case of commercial contactors, the aux contacts can often be added or stacked by add on units if the unit does not have or needs extra.
You have to define 'setup'.
Max.