Ceiling AC -- any mods to direct the cold air?

Go to Lowes or Home Depot, and go to the area that stocks ac registers, the grills that fit into the floor for the ducts.
Look for an item called a "diverter". These go over the register and devert's the air flow. Ususlly held on by magnets, but you can probably modify one to attach to the ac unit. Their usually made of clear plastic, and are adjustable. Use some velcro on the deverter and the ac unit to attach it so it's removable during the day.
Grumpy