"Install Subversion...
sudo apt-get install subversion
... and download the ubuntu-system-panel sources:
mkdir -p ~/Downloads/SVN
cd ~/Downloads/SVN
svn checkout http://ubuntu-system-panel.googlecode.com/svn/trunk/ ubuntu-system-panel
Afterwards you can install ubuntu-system-panel as follows:
cd ubuntu-system-panel
./usp_update install fresh"