It's not possible to use B3 as an FX. It has no audio input and is not made as a FX plug-in.NI B4 is a old discontinuet product that came both as a instrument and as a FX version to use as plug-in.It's possible to find Leslie or other rotary or tremolo FX plug-ins - also some even in DAWs own FX arsenal.You can search the web. And also study DAWs.Perhaps someone know of a awesome Leslie FX to recommend.