Hi Marco,
If the previous settings are from Compressor 3 then all you have to do is drag the settings from the Custom settings folder in the previous Compressor application to the Custom folder in your new Compressor application. The settings can be dragged to the Desktop and then copied to a drive or moved over the network.
If the settings are from Compressor 2, then you will need to drag them from the Home/Library/Application Support/Compressor folder on the old system to the Home/Library/Application Support/Compressor folder on the new system.
Hope this helps!