I have prepared 10 pound bags of sugar by soaking them in about one cup of water and allowing them to harden.
To fit in a 5-frame nuc box I cut the opening in the side.
A piece of wax paper or plastic wrap is used to hold the sugar in the bag while inverting the bag into a baking pan/dish.
A cup of water is enough to saturate the bottom inch or so of the sugar.
Allow several days for them to dry.
Like fondant, I place the bag directly over the openings in the inner covers. The hardened layer of sugar prevents the rest from cascading into the hive.
A hive body is used to house the bag of sugar.
Here is one that had been worked on by the bees...
I generally do not break the inner covers loose until the first warm days of February or March. The sugar bags may be an economical alternative to fondant, and like fondant (over the inner cover), there's no need to open the hive in winter.