Woodstock,
Those aluminium guide jaws and the plastic inserts are available, I have just replaced mine which were missing.
If I remember correctly, you don't have to remove the window in order to fit the slides. I had to because all my slides and guide jaws were missing. Try not to mess with the winder mechanism because it will take you days to get the adjustment correct again.
By the way, there are no felt strips in the window guides as in conventional cars, except for two on top of the door.
Regards
Chris