Is it possible to use AA miles for a trip using different one world carriers. If so, how is it calculated and what is the procedure to book it?

Currently I have about 90K and I know that it's very limited but ultimately I want a goal I can reach. For example, I'll be flying out of NY and let say I am interested in going to Austrailia and one of the one world partner has a hub in hawaii that also happens to fly to Austrailia then that'll be really great. Or maybe if I fly Cathay and since their hub is in HK, I can visit HK and then to Austrailia?

Any advice is greatly appreciated.

Since you are using AAdv miles those over in the AA forum would be the wisest source of info (although I am sure some on here would know too).

In addition to the AA forum, where issues of the new AA award charts (such as stopovers) have been discussed, I'd check out the airline partners page at AA.com:
http://www.aa.com/apps/AAdvantage/Vi...artnerType=Air

The ones of most interest (given your query) are:
the all airline award chart:
http://www.aa.com/content/AAdvantage...ne_chart.jhtml
http://www.aa.com/apps/AAdvantage/Vi...artnersContent

Those cover most of the basic award options.

If those are too restrictive, you can claim oneworld awards, which are mileage-based:
http://www.aa.com/apps/AAdvantage/Vi...artnersContent

I'm not an expert on the new chart and its rules, but from what I understand:

There used to be a Cathay Award that allowed travel from NA to Australia/NZ and South Africa, with stopovers in HKG. However, under the new chart that routing would require two awards- NA to Asia2, Asia2 to South Pacific or a oneworld award.

For a NA to South Pacific award, I believe you're now limited to one stopover- NA to South Pacific might be able to be routed JFK-LAX-HNL(stopover)-SYD-LAX-JFK, but, once again, I don't have any real experience with the new chart. You already have enough miles for a coach ticket to Australia, 35K more to go for a biz ticket!

AA has one world awards based on miles flown. For example, CGK - SEZ would count only as travelling 3520 miles (which means using 35 000 economy or 75 000 business) even though the routing would be CGK HKG JNB NBO SEZ (11 780 miles) or possibly CGK HKG LHR NBO SEZ, so it is only the distance between start and end point. You can have as many points as you like, and you have to be sure to use at least 2 different carriers in order to use the ticket.
Details here:

http://www.aa.com/apps/AAdvantage/Vi...artnersContent

I find that very hard to believe - if what you say is true then one could fly more or less indefinitely for the price of one award. My reading of the OneWorld Awards is that it is the actual distance flown which determines the number of miles required.

This is not correct. Unless it is a through flight, the miles of each leg add up.

Unless AA has changed, flyinghigh is correct that AA calculates origin/destination and not by flight numbers. The other carriers are by flight numbers as usual.

So what is to stop me flying HKG-LHR-JFK-SYD-MNL for the price of a HKG-MNL award?

It's definitely not the actual distance--for example JFK-LHR-JNB is measured simply as JFK-JNB...but I don't know about the examples given above, They may well be the same (obviously you can't stop-over at any of those places.)

Why would someone do that on an award ticket? Stock in Preparation-H? Collects amenity kits? Wants to catch up on movies and too cheap to rent them?

I am sure that at some point the ticket agent will ask you the same thing and probably tell you to stop screwing around and to get to wherever youre going. But airlines do things every day that baffle me and it doesn't mean that whatever they do doesn't exist.

more discussion of this issue here:
Most efficient OW Award ticket request
http://www.flyertalk.com/forum/showt...3&page=1&pp=15

Including examples such as the following:
"You can get fairly creative with the routing. For example, I booked DFW-DEL as part of my RTW, but gave the agent enough restrictions so that the only realistic route was DFW-LAX-HKG-DEL (which I wanted) rather than shorter, and more obvious, routes such as DFW-LHR-DEL.

Result: like the OP stated, it was fairly easy to construct a sub-20k mile OW130C RTW trip, even though actual flown mileage was significantly more than 20k."