Build a normal dungeon room, empty in the middle as always. Build two columns of unwalkables one combospace away from the two left and right sides of the room so that it looks like this:
[font=courier]
XXXXXX
XXXXXX
XX
XX X
XXLX
XXLX
XXLX
XX X
XX
XXXXXX
XXXXXX
[/font]
... ... and the mirror-opposite on the other side of the room. Doesn't have to be the upper and lower sides of the room, as they appear to work just fine.
Give yourself the ladder, and walk more towards the middle of each side of the screen (Where the L is.) next to the walls between the unwalkables.
You'll find yourself stuck, either on the ladder, or as if you were within a bunch of unwalkable combos.
EDIT: ZC Movement is not on. I actually imported a 2.10 quest into this and activated a few of the quest rules, but nothing relating to movement.