The main tab new, edit and other scripts allow you to manage the object tab from the main menu.
Create scripts in the appropriate add-in. For Pages, Editions and Tracking main tabs, use Fred.vb (Fred4WindowAddIn class), for all others, use Shell.vb (WindowAddIn class) or Ted.vb (Ted4WindowAddIn class).
The example below is about contact object.
Public Sub NewContact()
Dim objectId As Integer = NewObjectDialog(Main, "contact", False)
If objectId <> 0 Then
OpenDesigner(objectId, OpenMode.ReadWrite, Nothing)
End If
End Sub