I don't believe it's possible to cross from 9x19 to .40/.357. You can convert .40 to .357 and vice versa, but the 9x19 guns have a fundamentally different slide. If it were possible to convert a 9x19 pistol, you'd need a whole new top end, which would cost you so much that you might as well buy a new pistol.
Note that you can cross from .40/.357 to 9x19 via a conversion barrel.