Thanks, rharv. I gave that a spin. Not a perfect solution, but it gets me started.

In my inbox at lunchtime was a link to the latest release. In it was this. ", RealCharts for existing bass RealTracks". If I understand things correctly, this would allow me to the right click and "Select Whole Track -> Generate MIDI -> Bass" like I can with the drums? That might be worth the $150 right there.