The easiest way is to use a DAW.

Export your tracks from BB or RB to a DAW and use volume envelopes to bring things in and out as needed.

That's how I do it. I choose the path of least resistance when I'm working on music. I don't want to get bogged down in trying to figure out how to do something complicated when there's a much easier way to do things.

ALL of my songs are done in this very manner.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.