Qt Eclipse Integration and custom widget plugin

What is the correct procedure to compile a custom widget with the Eclipse Integration plugin, under Windows with MinGW?

I tried the following steps, but I cannot see the widget in the Widget Bar.

1. Installed Qt 4.6.1 for Win32 (with MinGW)
2. Installed Eclipse Helios 32-bit (tried with Galileo too)
3. Installed Qt Eclipse Integrator 1.6.1
4. Reconfigured Qt for Integration: configure -release -qtnamespace QtCppIntegration
5. Compiled plugin in release using Eclipse (tried with Creator too)
6. Copied DLL file e "a" file in folder C:\eclipse\plugins\com.trolltech.qtcppdesignerplugins.win32.x86_1.6.1
7. Launched eclipse -clean to reset plugins

Naturally the widget works well under Qt Designer and I can use it there correctly.