I think it is going to be very difficult to have AKL-MSP be the open jaw.

Note: As of June 15, CO rewards actually get one stopover and two open jaws. You are pretty much guaranteed having to call in if you want to book all of those as I don't think the website can price out both open jaws.

I was able to get the CO website to price out MSP-JNB (stopover) JNB-BKK (stopover) BKK-AKL for 62,500 miles. Whenever I try to throw in the AKL-MSP leg it breaks though. You may be able to get them to make this happen if you do some open jaws that are short instead like MSP-CPT (open jaw) JNB-HKT (open jaw) BKK-AKL (destination) AKL-Europe (stopover) Europe-MSP. Theoretically you could price that entire itinerary for 80,000 miles, but I don't know if it's possible. That would be a RIDICULOUS ticket.

The only firm telephone agent rule is that you must cross the same ocean as you did on the way otherwise it becomes RTW.