Is it possible to make custom Culture / Region combinations?

I would like to support someth开发者_JAVA技巧ing like a NL-Us culture. Is this possible?

Yes, it is.

You need to start with CultureAndRegionInfoBuilder - the link above is a full howto on MSDN.

A quick search found fellow MVP Paulo Morgado, who has created a tool for setting up custom culture and region information: http://www.codeproject.com/KB/dotnet/CultureAndRegionInfoTool.aspx

Not sure if fits your need, but the question WAS rather open ended. Hope this helps.