Maybe it is easier for your use case to use separate portals per language and not using ML features at all.

Enzo,

You might be able to acheive what you want by adding some code to the Page_Load method of your skin.  (and also removing the language selector skin object)

Something like this.

                If Request.Url.Host = "www.mydomain.co.uk" Then
                    System.Threading.Thread.CurrentThread.CurrentCulture = New System.Globalization.CultureInfo("en-GB")
                ElseIf Request.Url.Host = "www.mydomain.it" Then
                    System.Threading.Thread.CurrentThread.CurrentCulture = New System.Globalization.CultureInfo("it-IT")
                ElseIf Request.Url.Host = "www.mydomain.de" Then
                    System.Threading.Thread.CurrentThread.CurrentCulture = New System.Globalization.CultureInfo("de-DE")
                Else
                    System.Threading.Thread.CurrentThread.CurrentCulture = New System.Globalization.CultureInfo("en-GB")
                End If