Hi irishflyboy and happy New Year,

You could definately do this as a Oneworld Explorer. A few things to keep in mind. First, the fares ex-Ireland are pretty high and you could get a better deal starting elsewhere. Second, on a Oneworld Explorer, you pay by continent and your second proposed itineraries are for five continents, making it more expesive. Third, there do not seem to be flights between all your chosen cities, so you will end up flying more flights that those you have listed.

Here is a proposed itinerary for your first suggestion.

DUB-LHR on EI
LHR-CPT on BA
CPT-JNB on BA (operated by Comair)
JNB-HKG on CX
HKG-SYD on CX or QF
SYD-LAX on QF
LAX-DUB on EI

This a seven segment itinerary, but keep in mind you get up to twenty total segments and you could do more in Asia, Africa, Australia and North America. The fare basis for this would be DONE5.

For your second proposed routing, this itinerary would work:

DUB-MAD on EI or IB
MAD-JNB on IB
JNB-CPT on BA (Comair)
CPT-JNB on BA (Comair)
JNB-PER on QF
PER-SYD on QF
SYD-AKL-SCL on QF or LA
SCL-LAX on LA or AA
LAX-DUB on EI

Once again, you could add segments in any continent if you chose.

Good luck. Planning these is almost as fun as traveling on them!