Note: With e-ticketing, there is a function called "Present Credit Card" indicator, also known as "PCC".

When purchasing tickets over the phone or online, some airlines (I know CX does this for their website) would add the PCC to the e-ticket record. This is done to prevent fraud.

With the PCC in the e-ticket record, the passenger would be required to show the credit card used to purchase the ticket at check-in. If for whatever reason he cannot present the credit card, he will be denied boarding unless he makes another payment either by cash or another credit card. (In the case of CX, for third party bookings, the credit card holder will need to visit a CX office to sign a credit card slip)

So in theory, you can have the carrier price the XONEX using the price as if it was sold in the country of origin. Then you would call the carrier's ticket office in the country of origin and give them your credit card number. The carrier should have no problem accepting the credit card as they can input the "PCC" into the e-ticket.