Should be possible. There are flight options LIM-JUL with a stop at CUZ, but the website will be useless, you'll need to call. Here is the terms and conditions if you need to quote them:

11.2 The Awards allow one (1) Stopover (voluntary stop of the passenger on one of the Stops included in the outbound section or return of the trip) or one (1) OpenJaw (destination city other than the origin of the return flight,) on both domestic and international routes.

1.13 Stop Over: is a stop between the origin and destination, where a passenger can stay for a certain time, then continue the journey to their final destination on the same airline.

1.14 Open Jaw: flight for which the destination of the trip is different from the origin of the return segment (i.e. a trip from Santiago to New York, returning from Los Angeles to Santiago.)

1.15 Stop: a technical stop between the origin and destination points, at which a passenger must stay (usually on the plane or in the airport) for a short time and then continue on to their final destination.