Mainline Repository and Release Tarball
The project page for this tool is on Bitbucket https://bitbucket.org/dirkbaechle/scons_qt4. There you can find more infos about how to get the sources or download a release tarball, but it is recommended to use Mercurial to branch the mainline branch -- a form of continuous release.
Based on the code mentioned above, Russel Winder set up a Bazaar branch of this tool on Launchpad https://code.launchpad.net/~russel/sconsaddons/qt4 (deprecated, please use the Mercurial/Bitbucket branch instead!). Philippe Vaucher and Dirk Baechle then set about making various additions and fixes to create a production version of the tool. The current mainline can be found from the project page at https://bitbucket.org/dirkbaechle/scons_qt4.
If you are interested in compiling Qt4 apps/libs with SCons, you should have a look at its manual:
and/or the doc archives:
and then get the latest code of the tool. More detailed instructions for this, can be found on the page of external SCons Tools, the so-called ToolsIndex.