deltame

Yes, its doable via this approach. If you already have a travel bank/gift registry setup in your account, then its easier to use that to charge the gift amount using your first card (either a credit card or a prepaid gift MC/AMEX). The $ amount will then be shown (deposited) into your travel bank and can be used to pay for ticket purchase (either alone or with another credit card).

One thing to keep in mind, when using prepaid gift MC/Amex, is that the airline would first verify your payment by a trial charge in the amount of $1, then proceed with charging the purchase amount. If you charge the whole balance of your prepaid gift card, the charge may not go thru. Therefore you need account for the trial charge (temporary hold) by reducing the total payment by $1 from your current balance. Typically the trial charge ($1) would come off of your payment account in 7-10 days. I've done this before with prepaid Amex gift card and I always registered my gift card (name, home address, etc) with Amex, to prevent other issues with online purchase.