Okay, so you're interested in trying the Lexmark 5700 driver for ghostscript.
Ghostscript is a big, powerful tool, which can be compiled to run under
many different operating systems.  That's good, after you've done it, but
it presents a hurdle right now.  

I can offer a little generic advice, but I've only recompiled under linux,
and if you're already using linux, you probably don't need my advice.
Here goes anyway:

1) Download the ghostscript sources and unpack them into an appropriate
directory.  In my case, I got the Aladdin 5.50 sources from 
ftp://ftp.cs.wisc/ghost, and I picked up sources for three libraries used
by the program as well, the jpeg library, the zlib library, and the png library.
I was willing to drop features to download fewer files, but was unwilling
to work hard enough to figure out how to do without these libraries.

1.5) Expand the files.  Since I am running linux, I already have
gzip and tar on hand.  The command was something like
 % tar -xzf gs_5.50.tar.gz
 % cd gs5.50
 % tar -xzf ../libpng.tar.gz
 % tar -xzf ../jpeg-6b.tar.gz
 % tar -xzf ../zlib.tar.gz
which creates a directory structure on the disk.  In my case I now had
the sources in /gs/gs5-50/gs5.50, and I subsequently wished I'd been a little 
less eager to mkdir gs and gs5-50.

2) Pick up the driver source, gdevlxm.c, and the file contrib.mak, from my
web page, and place them in the source directory with the other driver sources
and .mak files.  There is already a contrib.mak there, and you may want to 
confirm, before clobbering it, that the one you got from me doesn't
omit something else you want.  If you're downloading 5.50, you're safe.

2.5)Among the 1200 or so files in the source directory 
are several .htm files which offer advice on building
ghostscript.  If your environment is not exactly like mine, you'll 
probably end up reading them very carefully, but if you're with me so far,
plunge on ahead.

3) The compilation process is laid out in the .mak files, which is 
why you need to have a contrib.mak that mentions the lexmark driver.
.mak files are input to the 'make' program, and if you're running a 
unix system, you probably have one already.  If you have a microsoft
C compiler, you have 'nmake' hidden away somewhere.  If you don't have
a 'make', you'll need to get one, unless you're very patient.  I think
there's a pointer to the GNU make sources at ftp.cs.wisc.edu, so if you
don't have a 'make', download and build one.

4) decide what environment you have, and how it matches the available
.mak files.  I used unix-gcc.mak which is for unix-like systems using the
gcc C compiler.  You might have Microsoft Virtual C (msvc32.mak) or 
Borland C, or Watcom C, each of which has an appropriate .mak file.
If your decision diverges from mine, of course, you're on your own.

5) I edited unix-gcc.mak to change the DEVICE_DEVS6= line to
DEVICE_DEVS6=lxm5700m
doing so discarded the other devices which were mentioned on the line
previously.  That means that the capacity to deal with them will not
be built into the version of ghostscript that I have.  That's okay,
because I don't happen to have those devices, but you probably want
to think about what if anything you want to delete.  In any case, having
gone this far, you need to add lxm5700m to one of the DEVICES_DEVS= lines.
There are some nearby comments describing the process.  If your environment
is different from mine, you will likely be editting a different file,
for example if you expect to run ghostscript under Win 95 and you have
the MS VC compiler, you will make this edit in msvc32.mak.

6) I typed 
  make -f unix-gcc.mak
and went to bed. Your computer may be faster than mine, but this next step
takes awhile.

7) The resulting file can be installed with
  make -f unix-gcc.mak install
but I actually moved the files around by hand.  There are initialization
files, which need to be moved into the directory described in 
unix-gcc.mak as GS_LIB_DEFAULT.  Since I hadn't changed this in step 5,
gs will look for them in /usr/lib/share/ghostscript/5.50, and that's where
they need to go.  Fonts should be moved, too, except that my .dvi files don't
need the ghostscript fonts, so I didn't download them.

8) Once the files are in place, you can use the Lexmark 5700 driver 
with the command
  gs -dHeadSeparation=15 -sDEVICE=lxm5700m -sOutputDevice=/dev/lp0  postscriptFile.ps

where 
      -dHeadSeparation is an optional parameter describing your print cartridge.
      -sDEVICE=lxm5700m means that the bits to send to the device should
        come from the gdevlxm driver you've just built in.
      -sOutputDevice=/dev/lp0 means that the output should be sent to the
        lineprinter port.
and  postscriptFile.ps is the name of some postscript file.	

Other switches I use are:
      -NOPAUSE means don't ask for confirmation on every page of output.
      -q means 'quiet' and slightly reduces the number of Ghostscript messages.
      -dBATCH means Ghostscript should terminate when it has finished with
       this command, instead of entering interactive mode.

All of this except for -dHeadSeparation is documented in the file 'use.htm'
which comes with Ghostscript sources.   The HeadSeparation parameter describes
the print cartridge you're using, and if you are particularly careful, you'll
use a different value for each cartridge.  The Lexmark 5700 black cartridge 
has two print heads, which are about 16 pixels apart.  When you install 
a new cartridge under Windows, you are given an opportunity to set 
alignment options, and the HeadSeparation parameter is one of them, 
'Black Bidirectional Alignment'.  The others pertain to color, which 
this driver doesn't support.  If you omit the parameter, you'll get the 
default value, which is 16, which gives reasonable-looking output most of
the time.  You can get an interesting special effect by deliberately using
wrong numbers.