I am not sure Max/MSP is really good for live coding - you have to recompile the dsp, It does not really do loops or any situational programming, and patching stuff up just takes ages.
So I am going to try and prove myself wrong hopefully with other peoples help.
You can get Max/MSP at http://www.cycling74.com
The idea for this project came from http://www.eude.nl/projects/max-live-coding/
and TOPLAP do this kind of thing http://www.toplap.org