This is the core of the installer.
svn co http://svn.xfce.org/svn/xfce/installit/branches/installer-single-file installit cd installit ./autogen.sh make sudo make install cd ..
svn co http://svn.xfce.org/svn/xfce/xfce-installers/trunk/xfce44 xfce44-installer cd xfce44-installer
Update the version number and whatever else you want in xfce44.xml, the configuration file for the installer.
mkdir release cd release
Acquire a fat tarball and place it here.
tar -xjf xfce-*-src.tar.bz2
That'll create a xfce-…/src directory containing a bunch of .tar.bz2's. Extract each of those and move the resulting subdirectory up to the current working directory, truncating the version number from its name. (I have a script to automate this. -ongardie)
cd .. #back to xfce44-installer
make ./xfce4-*-installer.run --check