If you'd like to use more than one synth on your project, I'm afraid you're going to have to bite the bullet and use RealBand. Band-in-a-Box can only use one synth at a time, and the synth will have to be able to do every instrument, like guitar, bass, drums etc.

You can always use a General MIDI synth (like the VSC DXi) when putting together the tune in Band-in-a-Box, and then open the tune in RealBand, where you would apply your more specialized VST instruments to different tracks and add finishing touches...

If you don't like the sounds in the VSC, the Cakewalk TTS-1 sounds a lot better, in my opinion. You can get it by purchasing the Music Creator 5 package. www.pgmusic.com/musiccreator.htm. Only $39.

Thanks
Kent
PG Music