I assume you do NOT have a Factory Service Manual for your car?
IF the slide itself is stuck, you can probably free it up easy enough,
but you would need to remove the control panel from the console, so you
can get to the "guts" of the slide, in the rear. This involves removing
all of the little screws holding the radio/gauge cluster trim panel, as
well as the screws holding the shifter/center console top on. The
shifter console plate needs to be removed first, or the radio/gauge trim
panel will not come off(without breaking it!).
Once the cover/trim plate is off, you will be able to see the screws
holding the Climate Control panel to the dash. It's been a few years
since I have been behind the dash of one, so I'm a little rusty on the
specifics of what all might need to be removed/unplugged.
What usually happens is, the part that the slide actually attaches to
will be what is messed up. If I remember correctly, the slide actually
moves a circular control(vacuum switch) that simply directs vacuum to
different hoses going to the different doors in the A/C plenum, and
that's what re-directs the airflow thru the system. The circular switch
there can get stuck in one spot from the grease used on them getting all
hard.
Hopefully, you can simply remove the climate control head, and free up
the slide. You may want to try to spray a little WD40 on it and let it
soak a few minutes before trying to free it up. You'll want to move the
slide side-to-side a little at a time...back and forth. If it doesn't
look like it's going to move, or free up, the vacuum switch may be
toast, and need replacing.
I'll dig my service manual out and see if it has anything better on
this. If it does, I'll definitely get back with you sometime this
weekend. It's supposed to get down into the low 30s here tonight....a
heater is gonna be needed for us!
Hope this helps in some way, and I'll see what else I can come up with to help.
______________
Joel Adams 
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"
BATaylorEsq
Adams' Apple