[cups.general] how to add custom postscript at the head

[Evert Mouw]

I need to add custom postscript commands to get documents to print. 
Something like:

%!OCE *JEC BEGIN
%!OCE somerandomstuff
%!OCE *JEC BODY
%!PS-Adobe-3.0

So, even before the PS-Adobe line.

I was playing a bit with the PPD file and downloaded the PPD specs. It's 
stupid, I tried for hours, but I could not find out how to do this, 
although it should be simple...

Any hints?

Thanks, Evert