What I want to do is use BB to generate tracks, then replace those tracks with me playing. I have not figured this out yet. (I'd say I'm disappointed but I know it's my ignorance, not the program's capability, which is pretty impressive.)
This is how I use the program. Of course, it's only one way out of many.... chose what works for you.
1. I write the song in Band in a Box. All verses, choruses, etc are put into the proper structure, tempo and key are selected and finally the style....rock, country, etc. When it's right I save it.
2. I open the project in Real Band. RB populates the tracks with the BB tracks according to the style from BB. I select the longest track in RB and then use the track generator to add new tracks for instruments not in that style. I normally write in a rock style but RB lets me add fiddle and steel as well as anything else I want. I save that file.
3. I open Sonar (by Cakewalk) and import the tracks I created and rendered in Real Band into the new Sonar project. I do mixing, EQ, reverb, and add vocals as well as my live guitar and keyboard parts in this stage. When I am finished, the project is ready to be exported as an almost finished song. I export the wave.
4. I open my Wave editor and load the "finished wave" from Sonar. I trim the start and end, and add final touches to what is now the finished song.
And that's how I do it.