Hi:
I have to tell you that the S.A.2 Pan flute is totally different than the "stock" sounds, there is such a huge change in the dynamic range (touch) besides the Super Articulation.

I have purchase this premium sound(there are 2 Pan Flutes), to install this voice you need a USB Drive, I am posting the link you need to visit, is needed to generate on your T4 with a USB drive, and follow the instructions.

http://www.yamahamusicsoft.com/en/instrument/Keyboard/Tyros4/product/1173037?currency=USD

I do understand your concern regarding the Credit card issue, I suggest to purchase a Visa or MasterCard "Gift card", after you register it to it's seller, you can make purchase on line without linking it to your personal and or bank accounts information. This way is safe and no worries.
I hope it helps you.