Well, in theory the sequence of commands at the end of this post should work. If you want to use it to write a howto for a german website, as you appeared to suggest, experiment a little with the qmake commands as I'm sure there must be at least one too many in there. Try
ls /usr/qt
to see whether qt4 is really there (no idea how Ubuntu is laid out, and as you saw in my "script", Arch Linux has qt4 somewhere else completely).
You can also try qmake-qt4, at least, that's what's mentioned in
http://www.pokerth.net/component/option,com_joomlaboard/Itemid,58/func,view/id,51/catid,17/
svn co
http://pokerth.svn.sourceforge.net/svnroot/pokerth/trunk/pokerth
cd pokerth
export QTDIR=/usr/qt/4
qmake pokerth.pro
qmake
make
qmake
sudo make install