I think you'll have a hard time covering all 3 unless you can use the new LIM-IGR flight (I think there is one) and then IGR-AEP and then EZE-SCL-IPC. You might have to convince the agent why they should let you take LIM-IGR-AEP/EZE-SCL since it's a pretty circuitous way to get to SCL from LIM. They usually allow LIM-EZE-SCL since that is a published routing.

I think your best bet will be to book an open jaw using two one ways and a one-way intra S. America ticket. Book the inbound to IPC on the new LIM flight, book IPC-SCL-EZE-IGR with stops everywhere and then finally book your outbound open-jaw from IGR-AEP-EZE-wherever.