Actuall error messages and more detailed symptoms would be helpful. Without more details, I can only make guesses (and not even very educated guesses) as to what's going wrong.

I'll write this with the assumption that you're familiar with the Bourne Again Shell (bash) and are comfortable with Apple's Terminal command line. If you're not familiar with bash, ask again and I'll try and walk you through it.

You'll need to make sure your PATH environment variable includes the directory for the ant command (actually an sh shell script that uses the *nix shebang to pretend it's a binary). You'll also need to either have ANT_HOME set, or else have ant installed somewhere that ant expects to be installed (look at the bin/ant shell script to see which places it checks). The version of ant I have installed looks in /opt/ant and ${HOME}/opt/ant, in that order.

On Darwin (OS X), if JAVA_HOME isn't set, the ant script sets it to a sane default.

After you have compiled LW, you'll need to use runosx instead of run.