You must have Python 2.x installed.
On Windows, execute python tools\dfbuild.py -dtsm src build.
On POSIX, execute chmod u+x build.sh and ./build.sh.
The result of the compilation is in the build directory.
Set the Developer Tools URL to
file://path/client.xml, where path is the path to the client.xml file, for example
file://V:/Dragonfly/client.xml. Restarting Opera is not necessary.
You may also want to turn off usage tracking by clicking the Settings icon and unchecking "Track usage".