Video by PG Music Inc. via YouTube
Source
This video covers the steps for connecting a MIDI keyboard to Band-in-a-Box, selecting the VSTi/DXi Synth for MIDI playback, recording a MIDI track with the keyboard, and changing a MIDI patch.
Please note that this is on a Windows computer, and setting up a MIDI device with for Band-in-a-Box for Mac is a little different. Please feel free to contact us if you need any help!