If it's similar I just had to do the brake light on my son's 97 Taurus and
couldn't believe what was required.   In the sedan you have to remove push-ins
that attach a fiberboard cover and then in a very tight space remove 4 out of 6
visible nuts which can be seen once the cover is out of the way.  Of course
which two nuts you DON'T have to remove are not at all obvious until you have
actually removed all 6 of them.

That allows the entire lamp assembly to be removed from the outside of the car
after which you can finally give the bulb socket a quarter turn to remove it and
get at the bulb.

A terrible design from a service stand-point.

It doesn't come off from the outside.  At least not more than once.

Here's how it's done on a 2000 Taurus wagon:

High Mounted Stoplamp Bulb - Wagon

1. Remove the lift gate trim panel. For additional information, refer to
«Section 501-05».

2. Remove the rubber plug.

3. Remove the rear high mounted stoplamp nuts.  (I tried to attach a jpg to my
first answer but Giganews must have nuked it.  What the jpg would have showed is
if you look at the the liftgage without the trim you will see three nuts spread
out hortizontally where the stoplight fixture lies.  There is one nut on each
end and one in the center.  Then there is a fourth nut under the center nut...
looks to be three or four inches below the center one.  Hope this helps.)

4. Remove the rear high mounted stoplamp.

    1  Remove the bulb connectors.

    2  Remove the lamp assembly.

5. CAUTION:
  To prevent water from entering the luggage compartment, make sure the rubber
grommet is fully seated.

 To install, reverse the removal procedure.

That was me.

Here's the page...
http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0
c/0a/44/0900823d800c0a44.jsp

3. On the wagon, remove the lamp assembly trim cover at the top
   of the liftgate frame. Remove the two plugs, then remove the four
    retaining nuts retaining the lamp trim cover.

Here's the little picture...
http://www.autozone.com/images/cds/jpg/small/0900823d800c0a54.jpg

Here's the big picture...
http://www.autozone.com/images/cds/gif/large/0900823d800c0a54.gif

Here's an 86-95 Taurus/Sable/SHO-specific site, pretty much the same
as Autozone's (looks like the same manual)...
http://www.denniswolfe.com/Taurus/RepairGuide/Repair.htm
Chassis Electrical, Lighting, Signal & Marker Lights, then about
2/3 down in the right pane.

Later models are slightly different...
http://www.autozone.com/images/cds/jpg/small/0900823d801afe3e.jpg