Diacritical and cropmarks

[Dr. Antonio Botelho de Sousa]

One more time i need your help. I'm writing a book on medical statistics, and 
my print bureau wants me to send the files in PDF format, with crop marks.
How can i insert crop marks in the post-script output of a Lyx file?
Other question:
How can i insert diacritical marks, like y-hat or x with a little bar over, 
like the sample mean?
Thank for your help.

Dr. Antonio Botelho de Sousa
Portugal