Unless the Rental is yours, I wouldn't go cutting into ANYTHING w/o, first, getting the Landlord's permission. You would most likely end up having to pay damages.
There are retrofits for going through a window. Look into it and see if there's a 'temporary setup' you can buy where he'd only have to insert the 'hole' into the window while the dryer is on. DEFINITELY DON'T get an in-house dryer vent! If he gets one of those, next thing you know, you'll be asking 'us' why there's a mold and mildew problem.