I don't know about Amazon.de (I don't speak German), but at least for the UK version you need to have the following before you can sign up for a Amazon Payments merchant account:

* Have a phone with a UK-based billing address available for our registration service to contact you. * Have a credit card (issued by a UK-based bank) * Have a current account with a UK-based bank. (Optional; you can set this up after registration)

http://www.amazon.co.uk/gp/gateway-eu

So unless in you're in one of the few countries supported by Amazon Payments, you're out of luck (as far us Amazon Payments is concerned).