You access an IGatherLogs interface object by calling the IBuildCatalog.Logs method, as in the following example, where objLogs is the name you give to the IGatherLogs interface object:
Option Explicit
On Error Resume Next
Dim objSearchAdmin, objBuildCatalog, objLogs
Set objSearchAdmin = CreateObject("Search.SearchAdmin.1")
For Each objBuildCatalog IN objSearchAdmin.BuildServer.BuildCatalogs
Set objLogs = objBuildCatalog.Logs
Wscript.Echo objBuildCatalog.Name & " has " & objLogs.Count _
& " log(s) and will retain a maximum of " & objLogs.MaxLogs _
& " log(s)."
Wscript.Echo " The current log is " & objLogs.CurrentLog
Next
'Release objects
Set objLogs = Nothing
Set objBuildCatalog = Nothing
Set objSearchAdmin = Nothing