This is from the README:
The goal of the Blended Midi project is to create a simple way to controll Blender animations with MIDI time data. This is a ccomplished by using some Midi Libs I borrowed from ftp://ftp.cwi.nl/pub/jack/python/. The gui is plugin based and more plugins can be added with out too much work.
To install Blended Midi just unpack the zip file found at http://projects.blender.org/projects/blendedmidi to any directory. Then open the .blend file in Blender. In the "Main" text here are two variables found at the top wrapped in pound signs that need to be set for your path. NOTE. In Windows the slashes need to be forward slashes.
Running the program To start the program just hit alt-p with the mouse over the text window. Initaly starting the program may take a long time depending on how big your midi file is. The window is broken up into boxes for each track. The tracks are determined by the input file and should be visable in any good sequencer. The fist track will probibly be the info track, don't worry about this track, it will probibly be hidden in the next release. The next tracks are your music tracks. The name is the name that was set in the sequencer. The drop down menu, also on the tracks title bar, is used to choose how the track will be handled. For more details on see Plugins below. When everything is set up how you want it just hit the go button at the bottom. NOTE: This can/will take some time depending on how much information is in the midi file.
Plugins Drums The drum plugin is the original plugin of the Blended MIDI project. It takes keyframes from before 100 and copies them later on based on the MIDI time data. When the drum plugin is selected it shows a line for each note in the track, plus one for the NON note. The number farthest to the left shows the note number. Then number 60 is middle C and the rest of the notes go up and down from there with sharps and flats counted straight into the numbers. The next button is the start time. The range of frames to be copied are set by the start and end buttons. The Middle button is for the hit frame or the frame that the sound shold be synced with. The button at the bottom is the set the IPO that belongs the to the object the is being animated. The NOF note is played whenever a note lets or or has a note-off (NOF) event
Piano This plugin takes and an action from one object and copies it to several different objects. When selected the interface is simaler to that of the Drums plugin. The first row of buttons set the same values for the object that gets copied. The boxes below it are to set the IPOS to copy. The master is the Ipo to copy from. The base sets the IPOs to be copied to. The Ipo's to be copied to need to be named basename.note_number with notenumber in the form of 001 for numbers less that 100.
Final Steps I will not go into too much detail here since Blender 2.28 will have audio sequencing support, but I will give and overview. To mix the Sound and Video for the final movie you will need sound as a wave file. My perfered tool for this is timidity. Another option is to play back the file and record "what you hear" if your sound card supports that. To mix the sound and video I would use either virtual dub (www.virtualdub.org) in windows or transcode in Linux. I think in transcode the audio offset can be set in the interleve settings.