sending hexadecimal control characters, how to?

[Peter Alcibiades]

I need to send a plain ascii text file to a printer, which is going to be 
done, let's assume the file is printest, with

	cat printest>/dev/usb/lp0

Which just dumps the text file to that device.  There might be other ways 
to do it, but that is verified to work.

For this to do some other stuff, it needs to have hex 07 at the end of it.  
Probably very simple but I never did this before

How do you do it?  Do I have to use send a raw key ascii code number 
somehow?

Peter