You access an ICatalogSearchServerList object by calling the IBuildCatalog.SearchServers property, as in the following example, where objServers is the name you give to the ICatalogSearchServerList object:
Option Explicit 
On Error Resume Next
Dim objSearchAdmin, objBuildServer, objCatalogs, objCatalog, objServers 
Set objSearchAdmin = CreateObject("Search.SearchAdmin.1")
Set objBuildServer = objSearchAdmin.BuildServer
Set objCatalogs = objBuildServer.BuildCatalogs 
Set objCatalog  = objCatalogs("KMSampleCatalog1")
Set objServers  = objCatalog.SearchServers
...
'Release objects
Set objServers  = Nothing 
Set objCatalog  = Nothing 
Set objCatalogs = Nothing 
Set objBuildServer = Nothing 
Set objSearchAdmin = Nothing