Changing the Tempo
If you want to change the tempo of a MIDI file, do this:
Install the lilypond program (free from lilypond.org)
Open the file you want to edit (named in the form air_N.ly using the same Roman numerals as in the text) and scroll down to the bottom. The make-moment line works just like a metronome setting. Leave the second number alone—usually a 4 for quarter-note—and make the first number larger or smaller.