Once you successfully build jMax, you may create a snapshot. The recommended way to do it is to use a script provided in the jMax cvs.
From the trunk directory, do the following:
cd core/scripts ./make-release.sh
This will checkout the sources in a separate directory, compile and generate a snapshot tar.
The snapshot will be at ~/jmax-release/distrib.
This process guarantee that the built snapshot correspond exactly to the state of the central svn and do not include local modifications.