How to install Nightly build - Linux

Hi,
Because of some bugs in the pre release found in ubuntu ppa, I try to install the nightly build found there :
http://bernsteinforpresident.com/mscore-nightly/

I've downloaded the bz2 file and uncompress it. Then I've put it in /usr/bin instead of the original mscore.real file, and I've tried to launch the program entering mscore in my console.
it returns me this error :
/usr/bin/mscore.real: error while loading shared libraries: libQtDesigner.so.4: cannot open shared object file: No such file or directory
So I've tried to link the libQtDesigner :
sudo ln -s /usr/lib/libQtDesigner.so.4 /usr/bin/

And launch mscore again, I've the same error... :-(
So how can I do to properly install mscore nightly build on kubuntu 10.04 ?? I've found no documentation :-(