I think you should be fine with the "send passport, certified check/money order, copy of tickets, and return express airbill" strategy. However, I would also call AA/CX and see if alternate flights are available.

I was going to mention on the other thread where you talked about your trip that you should take the visa into account when deciding btw India or Thailand for your point for onward travel to Nepal, but I figured you knew about the visa already If your passport doesn't expire within the next five years and you intend to see more of India, I would consider requesting a five year visa (you probably won't get it, but it is worth a shot). As you know, you can get visas on arrival in Bangkok (and CX has plenty of flights daily out of HKG), so switching your BOM flight to BKK could be another option. You can get your Nepali visa on arrival at the Kathmandu airport.

FWIW, getting an Indian visa at the consulate in Kathmandu takes a full day.