Download the Eclipse distribution 'mosaique4eclipse' from Sourceforge and unzip it to your Eclipse 3.x /plugins folder. Re-start Eclipse and find the Mosaique view under Window/Show View/Other.../Mosaique/.
Download the old stand-alone distribution 'mosaique' from Sourceforge and
unzip it to your programs folder. Invoke run.bat to start it.
Please note, that the Swing interface is limited in features and will not be further developed.
Consider to use the Eclipse edition.