Sounds like you have ducts running through chases or an attic and venting down through the ceiling. These are normally connected to the air-handler with flexible duct. You need to get access to the ductwork / attic and see how things are configured. Its really pretty easy to move a vent, but you need to match up duct size and splice in.
Post back with what type and size of duct you are dealing with. FWIW, crawling in attics or tearing out ceilings is not one of my favorite jobs either.
.
