I use LoopBe30 for internal MIDI routing. MIDI Yoke would work too.

Pick up midiOUT VST
http://www.thepiz.org/plugins/?p=midiOut

Add to a plug in on an extra midi track you're not using, For example the "Soloist" track.

Set midiOUT to say "01: Internal MIDI"

Turn on the Conductor, "Enable control by Midi keyboard"
Set the MIDI in of Band in the Box to "01: Internal MIDI"
Yes, the same as Midi out from the soloist track.

Notes you add to Soloist track will now control the Conductor.

Add some C4 notes to the soloist track over the measures you want to increase tempo. The "Tempo" box will track these changes.

Each time a C4 plays the tempo will increase by 1

As midi is sent to the Conductor, you'll get the yellow tag pop ups like "Increase Tempo by 1"

This a very interesting way to add a "control" track to BAIB. Pick "Show MIDI notes" in the Conductor to see all the options.

The midiOUT VST is handy to send MIDI to any external midi. Band in a Box now sends out timing data also. A example might be to send out MIDI that mimics a controller from BIAB to Ableton.

Give some of these a try and post your results! smile