Hi, Does anyone have any advice on installing windlace without removing the headliner. I would like to leave the headliner in place as it is in good condition. Thanks!!!

I have done this. Is it stock windlace or something you are fabricating?
The trick is to install it without loosening the tension on the headliner. You should familiarize yourself with how the headliner and windlace are held in tension.
Basically there is a toothed piece of metal that runs the length of the roof line that is held under pressure against the body and the fabric that is inserted between this tooth is 'snagged' and can be difficult to release. Kind of a one way toothed cam if that makes sense.
I would use a wide putty knife and insert it in a fold of the excess windlace fabric and push it up between the body and the headliner. You might have to sew on an extra width of fabric to give you enough material to grab onto - push the fold up until the windlace is tight against the headliner, then release the excess you've been holding onto (which has allowed the windlace to be pulled snug) and the push the excess fabric up as well. There may be a better description of this in the manual.
Patience is probably the most valuable skill required in this job.

Thank you Danny. It is windlace that we have purchased (not fabricated). Phew! Patience, huh?? I think our other concern is getting that old one out without messing with the headliner. Your description does help with installing the new one. We were considering something with a masking tape to snag onto those "teeth".

When you go to remove the old one, again, I would use a wide putty knife and slide it up between the windlace and the headliner so as to release the old windlace from the teeth (albeit the teeth are grabbing the headliner first and the windlace secondarily), moving it along as you slide the knife up and down as you carefully pull the windlace down.

The new windlace has an excess fabric edge which, although long enough to be grabbed by the teeth when in place, may not be long enough for you to grab it's edge, create a fold for the putty knife, and still still be long enough for the teeth to grab while you are installing. This is why I suggest sewing an additional piece of fabric onto that edge. Tape might work, but it might work against you, getting stuck on the body or the headliner. Again, if the fabric edge is wide enough, this may not be an issue. Make sense?

If the liner is original, it should, I think, have been folded around the flange. It might even have had a smear of glue too. It that's the case it will likely stay in place if you carefully peel off the windlace. Reinforce with a strip of duct tape and fit new lace. That sounds too easy but I did change over an early cloth headliner to a plastic one on a '61 Amazon and don't remember any problems.