This is very simple to do.
Mount a scrap block on a faceplate and apply pressure using the quill advance between the bottom of the bowl and a live center mounted to the tail stock.
I'm going to dress the tenon and make it round again. Bowls tend to warp or go oval a bit when turned cross grain as this one was. Unfortunately, I took too much off of the sides to make the whole bowl round again, so it will have to be oblong. Dressing the tenon will allow me to put the bowl in a chuck and sand it at least so I can finish this bowl that has been drying for 2 months now. I want this done and off my shelf.