Your timing is !!! (but a wee bit sooner than we are ready for). We are working on a new set of instructions for installing and will be adding the instructions to the various ai4a 'places' in the next few days (but not today :-().
The short story
make sure you have a good Java JDK (java -version)
make sure you have JAVA_HOME set correctly (echo %JAVA_HOME%)
then you go to ...\AppEngine and click on startAI.cmd
and go to ...\BuildServer and click on launch-buildserver.cmd (or launch-buildserver32.cmd if you have a 32 bit OS)
and go to localhost:8888 in your browser and follow the instructions to app inventing joy
if things go less well, let us know here what happened.
Gary