Called AA ATW desk and booked the itinerary in less than 10 minutes. I initially called JL to arrange this ticket but the agent in Tokyo did not communicate well in English.

AA agent was really helpful and told me that AA would not have a problem issue this itinerary (though there are no AA segment) for me. So, tomorrow, I send $$$ to AA office in Korea and they will issue the ticket.

I will know the tax amount tomorrow so I am hoping that it won't be too bad. The AA whom arranged this itinerary for me said I should expect taxes and surcharges to be around 600 USD (~900,000 KRW). In worst case, I'd accept upto 1,300,000 KRW since I have many long segments (to maximize miles - but also I am visiting all the places I really need to visit ).

Thanks all for your help with this! You guys have converted me to OW flyer now (used to be very loyal to *A for the last six years or so - never stepped my foot in a OW carrier during this time).