You can get a .zip with all the classes the MS JVM uses by running "clspack -auto" at the command line. The output will be classes.zip will be in one of these directories, depending on your OS version:
that won't help him, as Eclipse won't use the Microsoft compiler which is a 1.1.6 compiler. Eclipse uses a 1.4.1 compiler (maybe 1.4.2 in current releases) which can sadly not be swapped out for a different version (my one major gripe with Eclipse actually).
So he needs a commandline 1.1.6 compiler. Maybe the Sun compiler will suffice if the required libraries can indeed be extracted, maybe not.