What do you mean by basis like what do you do in it?
Oh just saw your edit lol.
Have you ever done normal CBT? It is the same techniques only applied to psychotic symptoms. Learning how to change how you think about voices/delusions and how you respond to them, to put it in a basic way. It seemed to have a heavier focus on positive symptoms so I don’t know if I’d recommend it for someone who mostly has negatives when on meds but for positive it’s supposed to have a lot of benefit and help increase insight and all that.