How do you connect a vent pipe to the horizontal branch and main pipes running below the toilet floor of a high rise commercial building?

The toilet should have a 3" drain coming from the toilet and has to leave the room some where. When it passes the wall you can put a 3"x 2"x 3"sanitary tee( which should be going with the flow)and have vent stack running along the interior of the wall this may involve tearing out the drywall. Then just tie the vent on to an existing one. Keep in mind; the vent can be 2", and the vent can be no more than 4' away from the center of the toilet drain.