As you have just found out, it is not as simple as changing the language of a keyboard since although this may give you the QUERTZ instead of QWERTY you want, the other keys will display non-english characters since it is based on a keyboard LAYOUT and the alphabet of that country. You could, of course use the ascii codes for the Z in place of the Y but this would involve holding down the Alt key and typing in the cooresponding ascii numeric number for the z or Z which would not be ideal.
I think you can assign keys to certain letters, I just can't remember how to do it !!!
Perhaps someone else can remind me if this is possible.