Set the environment variable QTDIR to where Qt3 is installed.
   For example, in bash,   export QTDIR=/usr/lib/qt3

   To find out where Qt is installed. If you are using a binary devel
   package:

   In rpm based systems:
      - rpm -qa | grep qt
        tells you what Qt packages are installed. Say the devel
        package is called libqt3-devel-3.0.5-7mdk, then
      - rpm -ql libqt3-devel | less
        shows what is inside the devel package. ('q' exits less, in
        case you don't know).  You should be able to see a directory
        that is the _base_ of the Qt files. In other words, QTDIR is
        the directory so that
	    $QTDIR/bin  -> has files like designer, moc, qmake, uic
            $QTDIR/include  -> has qt header files like qaccel.h
            $QTDIR/lib  -> qt lib files like libqt-mt.so

   In debian based system:
      - dpkg -l *qt*
        shows which Qt packages are installed. If the devel is called,
        say, libqt3-dev
      - dpkg -L libqt3-dev | less
        shows the package contents.