[Visual Basic 6.0]
Public Sub OpenDatabaseLocatorWorkspace()
'+++ opens an ArcSDE locator workspace
    Dim pPropertySet As esriSystem.IPropertySet
    Dim pWorkspaceFactory As esriGeoDatabase.IWorkspaceFactory
    Dim pWorkspace As esriGeoDatabase.IWorkspace
    Dim pLocatorManager As esriLocation.ILocatorManager
    Dim pDatabaseLocatorWorkspace As esriLocation.IDatabaseLocatorWorkspace
    
    '+++ create a property set to specify the ArcSDE workspace
    Set pPropertySet = New esriSystem.PropertySet
    With pPropertySet
        .SetProperty "server", "napanee"
        .SetProperty "instance", "5190"
        .SetProperty "user", "sde"
        .SetProperty "password", "sde"
        .SetProperty "database", "sde"
        .SetProperty "version", "sde.default"
    End With
    
    '+++ open the ArcSDE workspace
    Set pWorkspaceFactory = New esriDataSourcesGDB.SdeWorkspaceFactory
    Set pWorkspace = pWorkspaceFactory.Open(pPropertySet, 0)
    
    '+++ get the locator workspace from the ArcSDE workspace
    Set pLocatorManager = New esriLocation.LocatorManager
    Set pDatabaseLocatorWorkspace = pLocatorManager.GetLocatorWorkspace(pWorkspace)
    
End Sub

[Visual Basic .NET]

    Sub SDELocatorWorkspace()
        ' open an ArcSDE Workspace
        Dim connectionProperties As IPropertySet = New PropertySet
        With connectionProperties
            .SetProperty("server", "SDEServer")
            .SetProperty("instance", "5151")
            .SetProperty("database", "sde")
            .SetProperty("user", "sdeUser")
            .SetProperty("password", "sdePassword")
            .SetProperty("version", "SDE.Default")
        End With

        Dim obj As System.Object = Activator.CreateInstance(Type.GetTypeFromProgID("esriDataSourcesGDB.SdeWorkspaceFactory"))
        Dim workspaceFactory As IWorkspaceFactory2 = obj
        Dim workspace As IWorkspace = workspaceFactory.Open(connectionProperties, 0)

        ' open the Locator Workspace
        obj = Activator.CreateInstance(Type.GetTypeFromProgID("esriLocation.LocatorManager"))
        Dim locatorManager As ILocatorManager2 = obj
        Dim databaseLocatorWorkspace As IDatabaseLocatorWorkspace = locatorManager.GetLocatorWorkspace(workspace)
    End Sub

[C#]

        public void SDELocatorWorkspace()
        {
            // Set up the SDE connection properties 
            IPropertySet connectionProperties = new PropertySetClass();
            connectionProperties.SetProperty("server", "SDEServer");
            connectionProperties.SetProperty("instance", "5151");
            connectionProperties.SetProperty("database", "sde");
            connectionProperties.SetProperty("user", "sdeUser");
            connectionProperties.SetProperty("password", "sdePassword");
            connectionProperties.SetProperty("version", "SDE.Default");

            // Get the Workspace
            System.Object obj = Activator.CreateInstance(Type.GetTypeFromProgID("esriDataSourcesGDB.SdeWorkspaceFactory"));
            IWorkspaceFactory2 workspaceFactory = obj as IWorkspaceFactory2;
            IWorkspace workspace = workspaceFactory.Open(connectionProperties, 0);

            obj = Activator.CreateInstance(Type.GetTypeFromProgID("esriLocation.LocatorManager"));
            ILocatorManager2 locatorManager = obj as ILocatorManager2;
            ILocatorWorkspace locatorWorkspace = locatorManager.GetLocatorWorkspace(workspace);
            IDatabaseLocatorWorkspace databaseLocatorWorkspace = (IDatabaseLocatorWorkspace)locatorWorkspace;
        }