Thread:Support/internationalization of interface messages in translate extension

I got help to add the translate extension. I'm new to this, but I've learn myself the very useful prefix. I try to make a multilingual website and are going to use this function a lot. Is it possible to make a similar prefix/template that I can point to another namepace than MediaWiki and that can work in the same way? Or even just include translatable text from the (main) namespace.