[NTG-context] Letterhead Usage

[henman]

I have created a letterhead for correspondence, but it is too unfriendly 
to have to include it in every time.

I would like to use it as a package, but don't know if it's possible.

The problem I see is that the command \setlayer must  be done after the 
\starttext command.
If it doesn't then formatting commands such as \sc  will not take affect 
and I believe a different font is also applied.

What would  be a user friendly way to implement letterheads (made up 
using the layers functionality of context?

Thanks