Robbie's suggestion of using  http://www.iammp.org/ is good.  This
group is currently scanning rolls using a Dyna Image contact image
sensor (CIS).  This is a piece of hardware similar to what is found
in many flat bed scanners.

If you want to learn more about MIDI files, I would suggest checking
out http://www.borg.com/~jglatt/tech/midifile/intro.htm  From there you
can learn a lot about the MIDI file format.  Something that it doesn't
do is give an example of a file and break it down into its components,
which would be useful to someone learning the MIDI file format.

Pete Knobloch