Another problem with venting into the wall is the general construction. Most of the time there is a board running across the top of the studs, this means with a wall on each side of the studs, sitting on the floor (actually another board), and a board across the top, you have a sealed box. If this is your condo and you really want to pursue this, you would need to go into the attic and cut a hole in the board that runs across the top and drop some 4" dryer vent down to where you have cut a hole in the wall. Or you could do the opposite and vent into the basement depending on what floor it is on.
The best option would be to remove the drywall between two studs cut a hole through the top and the bottom (to draw in cool air from basement/crawl space) and cut holes into the replacement drywall to fit the vent tubing. Should be about a 3hr job if you have the right tools and materials.
Good luck.