I am tackling the headliner on my 1991 C3.

[NIck Miller]

I'm not sure its the same but if it is similar or the same as  T44 I could
tell you, if anyone could verify.  Its pretty simple, I spose.

I guess you can start by trying to push the finish panel for the sunroof
backwards with a bit of force, and see if it will slide into the roof.  You
do that from inside the car, and just try and push the sunroof panel back.
You might need to retract it slightly to get to it, but try it without doing
so first.

After that, you need to remove the sunroof panel to get the headliner out.
There should be a piece of aluminum trim all around the headliner in that
area.  It has some tabs that fold over and hold this section to the roof,
and you can access them from outside of the car (on top) or standing through
the sunroof hole when it is removed, and bending them straight up and down
with a screw driver.

Should be about the same, again, this is my experience on a 91 V8 / 87 5ktq