Get source and compile
Even if you don't plan to develop, just the act of downloading and compiling can uncover problems. If the version you download doesn't build on your platform, file a bug.
Getting the source
Get the source code from the Get it! page on secondlife.com. Be sure to pay attention to the applicable licenses
Compiling
Per platform instructions are available for the following platforms:
See Common compilation problems if you run into errors while building.
Version control repository
We aren't yet providing live access to a version control repository. However, if you're interested in learning more about the subject, see Version control repository.