Well, without looking in the Wiremold catalog for specific fittings I would run the raceway down the wall (divider) with a "mouse" at either end. A "mouse" transitions from the raceway to a NM connector and will have 1/2"KO's. Install the top one right up against the ceiling with the NM entering it from above.
At the switch box location (or rather behind) use another "mouse" with a short nipple to go through the wall into the back of a cut- in box. You would strip your jacket from the NM after the connector at the top as usual.
Keep in mind that you can use this same basic setup to sleeve the NM. Then you don't need the connector, nipple and probably not even the mice. Just pop the wiremold up through the ceiling. Slide your NM through the wiremold and through a hole in the wall into a connector on the back of your cut-in box. Behind the box use a cut off outside 90 to cover the end and the cable.
-Hal
