Hi Rodriguez,
Native Instruments sell a SIMULATOR for the B3 organ which they call the B4. You run that software in a computer with a sound card and play it with your PSR via MIDI. You can use the B4 as another voice that way.
The sound of the B4 is quite real and I personally use it and like it a lot. Now they have come up with new preset files which allow the modeling of 'used', 'brand new', etch B3 organs, plus other classic models of other brands.
You can download the demo version at their site. Try this place:
http://www.nativeinstruments.de/index.php?home_us The B4 is very different from a PSR voice. It is more like controlling a remote B3 as you press your PSR keys. It has it's own controls which show on your computer screen.