I would like to install a new bathroom in my basement with a stand-up shower, sink and toilet. The problem is there is not a stub for the toilet I would have to cut into the concrete slab. My question is how do I go about vent he toilet or should I even worry about venting. There is an existing vert pipe coming from the existing drain for the lundry tub on the other side of the room.

" how do I go about vent he toilet or should I even worry about venting. There is an existing vert pipe coming from the existing drain for the lundry tub on the other side of the room."

In my area it works like this. First you come off the house main with 4" to the toilet stup-up 12 inches off the wall to the center of the stub-up. The lavatory will connect to the toilet main with 2" and a vent will come off the lav stub-out tee and run up and over and revent into the laundry tray vent or continue on through the roof. The showen will connect to the lavatory drain with 2" and be wet vented by it. The entire group can be vented by one vent unless local codes say otherwise.
Good luck, Tom