Hi,
I was not completely sure how the size GET parameter looks like and assumed something like 24_24
The code works for me with e.g. the following GET parameters:
action=Markup
coro_size=24_24
side=1
markup=anything
I added some styles. Find the script as attachment. I think the code can be improved a little bit but I didn't want to change too much of it.
EDIT: I oversaw the link in your first post so you might need to tweak the script a little bit.
Thomas