tbh I don't know the full specs of the 5600.
The 8800 is designated to 35mm film and slides and 120 format film ...there are suitable film holders supplied with the scanner.
I found it possible to scan glass plates purely by experimenting.
If the 5600 works like the 8800 then simply remove the protective sheet from the lid as you would to scan 35mm and as said before , place the glass plate directly on the scanner bed....As for the thickness of the glass plate, it shouldn't be any more than what the 35mm film holder would be so therefore shouldn't cause any probs when the lid is lowered...obviously be sure to watch carefully and take your time with the first attempt but I don't think you will have any difficulty with it.
Just to add, I used to have problems with very curly 127 film refusing to lie flat so now I trap the film between the scanner bed and a piece of clear glass from a small picture frame....again with no technical difficulties with the scanner.
Obviously it is up to the OP wether he tries my suggested method and ultimately his responsibility but I would not make a suggestion along these lines if i believed damage could be caused to his equipment......just use common sense whilst playing around.....good luck!