> 1. Make a printer filter text into postscript, but leave postscript alone.

   This is not possible without resorting to human help; PostScript _is_
   text (at least until you get into Level 2 binary encoding and such,
   which I assume is not what you're talking about).  Indeed, I have on
   occasion wanted to print _exactly the same file_ twice, once as text
   and once interpreted as a PostScript program.

I didn't see the original post, but there is in fact a way to do this
using apsfilter (it works great for me, anyway; or at least it did
before I ran into my 1.1 printcap problems :).  Here is an excerpt of
the docs.  I don't know if this is the most up-to-date version.

	  WHAT IS APSFILTER
	  =================

	  APSFILTER is a lineprinter input filter for systems with a BSD alike
	  printing mechanism (lpd, /etc/printcap), that saves users a lot of work 
	  when printing different file types no matter if compressed or not !!!

	  Additionally it enables non Postscript printers, that are supported
	  by the public domain postscript emulator "ghostscript" (gs), to
	  print postscript files automatically !

	  With the new apsfilter Version 3.0 it's now possible to print 
	  *compacted* documents directly without unpacking !!! 
	  The wanted packers/unpackers have to be already installed on your system.

	   o Supported packers:

		  GZIP, PACK, COMPRESS, FREEZE/MELT

	   o Supported file types:

		  Postscript
		  TeX DVI
		  Ascii
		  Data (PCL,...)
		  GIFF
		  TIFF
		  Sun Rasterfiles
		  FIG
		  PNM (pbmplus)
		  JPEG

	  ==========================================================
	  These are the sites, where apsfilter versions can be found
	  ==========================================================

	  (1) This ftp server will also contain beta releases if we are
	      currently on the way to a new release

		  ftp server:	ftp.informatik.rwth-aachen.de
		  directory :	pub/Linux/local/packs/APSfilter

   > 2. Disable banners.

   No idea.

See the following printcap capability:

	  PRINTCAP(5)               NetBSD Programmer's Manual               PRINTCAP(5)

	  CAPABILITIES
	       Refer to termcap(5) for a description of the file layout.

	       Name    Type    Default           Description
	       sh      bool    false             suppress printing of burst page header

Hope this helps.

Cheers,
Brook