Easter Island, for the purpose of the oneworld partner award is part of the South Pacific Zone, not the South America Zone. Making use of this award makes sense for those coming from the South Pacific, but not when you have to cross zones as is the case if you fly from the East. Another good way to reach IPC is with a oneworld award, which is distance based, not zone based, but that award is not applicable if all you want is to travel from a South America gateway to IPC and back.

For paid tickets the only sensible way to go to IPC is to make use of the South America Airpass (see lan.com), or as part of the oneworld explorer, a RTW fare.