On my 2004 Jetta it was one 6mm head screw. Need a long nut driver or a socket + extension(s).
While not required, it may be easier if you remove the blower motor & resistor, as that's just a couple screws holding it in, and you can then make sure the flap is engaged with the recirculation motor, or rotate it into position if necessary. (Assuming you've already removed the glove box... it may technically be possible to do this without removing it if you have tiny hands, but I sure don't!)