No. I put my itinerary together myself then emailed AA's ticketing office in Cape Town. On both occassions there has been no issue with me being based in Australia; they simply email you a simple form to complete with credit card details and also require a copy of your driver's license and the credit card used.
As for the AA segments, I've usually 'allowed' them to book me on an AA TAtl or even on the Pacific route. However, once it's ticketed I email CPT or phone the AA desk in Dallas or even in Brisbane and change the flights to BA (TAtl) and QF (Pacific). On one occasion there was some hesitation but I pointed out (i) I needed to be on the QF flight number in order to upgrade and, if they dig their heals in, (ii) there is nothing whatsoever in the rules that says a ticketing carrier must be used on the transoceanic legs.
Hmmm. Perhaps I was lucky. I'm in the very early stages of planning my next DONE4 and sincerely hope I'm lucky again. That said, the removal of the base pricing guide from the oneworld website for oneworld Explorers has some people concerned that a price hike is again on the cards.