g_fpsmode 1 allows you to move around and play normally in the "snipe" view (i forget what buttons the default binding for the snipe view, since i rebound it), so it basically turns the snipe view button into a toggle between first and third person.
there's also a bunch of commands you can see with the "help" command that shows all the available console commands if you're curious to mess around with stuff, although i couldn't find a way to completely turn off the third person camera's weird deaccel, but first person is completely unaffected afaik