Inspect the vent cover. Look for any holding screws. Remove screws with a Phillips screwdriver. Note that some vents may not have screws.
Pry off the vent cover with a flat screwdriver. Insert the tip in the small slit between an edge of the vent and the vent framing and pry upward. Use your hands to lift the vent out.
Pull the end of the cable or wire through one of the grates on each end of the cable before proceeding to Step 4.
Repeat Steps 1 and 2 on other AC vents that you want to run wires through. When you complete running the wires firmly press the vent covers back into place and reattach any screws.