how to plug qwt into qt-creator/designer IDE

Hi all, did anyone jet manage to integrate qwt-plugins into qt-designer? Believe me or not, I read the FMs, which turned out to be the "install"-file of the qwt package. I also read and tried whatever I could find in the web and in qt-designer-help.
I got QT4.5.2 installed on my WinVista-sys, loaded qwt-5.2.0 from the qwt-site, ran "qmake" on qwt.pro and created the whole qwt project - apparently successfully.
Then I followed instructions found in the web:
copied C:\qwt-5.2.0\designer\plugins\designer\qwt_designer_plugi n5.dll + libqwt_designer_plugin5.a
to C:\Qt\2009.03\qt\plugins\designer\....

copied C:\qwt-5.2.0\lib\libqwt5 to C:\Qt\2009.03\qt\lib\....
copied C:\qwt-5.2.0\lib\qwt5.dll to C:\Qt\2009.03\qt\bin\....

I can now create some of the qwt example projects - more or less successfully. However I do not find any manual or procedure providing a useful description to make the qwt widgets visible/available in the qt designer panel.

Anyone out there with a good hint?
Many thanks in advance.