You access an IMapping object by calling the IMappings.Item property. Since IMappings is a collection, you can access all IMapping objects using a for each loop, as in the following example, where objMapping is the name you give to the IMapping object:
Option Explicit
On Error Resume Next
Dim objSearchAdmin, objBuildServer, objCatalogs, objCatalog, objMappings, objMapping
Set objSearchAdmin = CreateObject("Search.SearchAdmin.1")
Set objBuildServer = objSearchAdmin.BuildServer
Set objCatalogs = objBuildServer.BuildCatalogs
For Each objCatalog in objCatalogs
Set objMappings = objCatalog.objMappings
Wscript.Echo "objCatalog " & objCatalog.Name & " maps the following:"
For Each objMapping in objMappings
Wscript.Echo " " & objMapping.From & " to " & objMapping.To
Next
Next
'Release objects
Set objMapping = Nothing
Set objMappings = Nothing
Set objCatalog = Nothing
Set objCatalogs = Nothing
Set objBuildServer = Nothing
Set objSearchAdmin = Nothing