NO buttons to push for LSD, at least on the TRD Sport. Its mechanical. Look at the axle, it should have a sticker saying so.
I beleive on some Tacomas a push button 'auto LSD' is available. But according to manual, they can use only in 2wd and up to 25 mph? maybe ok on a 2wd, but on a 4wd, whats the point? whatever, MY TRD Sport LSD in always 'on'