This is easy. Just call Card Services and give them your secondary address. This address will then be placed on the authorisations system and can be verified by vendors. I regularly do this with addresses in the US, and even here in the UK when ordering from online stores that can only deliver to the credit card address.

If you experience a declined transaction just call Card Serives immediatly and they will tell you why it has been declined, and then set the system to force authorisation if you try it again.

IMO this is a very very useful feature of buying power available when using Amex, and is a service very difficult to obtain from Mastercard and Visa issuers, as many of their authorisation systems are not as flexible as the AMEX system. To update it on-the-fly to force through a transaction at your request, and satisfy the vendor of verification information is excellent!