that should be possible too.... i typ this now by looking at the settings and the explanations with the settings in the ADNM console, not out of the manual (which u should read too!)
in the COMPUTER CATALOG create a new folder in which u place only the AMS mirror server.
right click on the folder and choose properties
in the properties menu list on the left choose POLICIES: MIRRORING
there you can set where to get the updates from
i believe there is a thread or more about this here on the forum too, use the search function for that...
let it know here if this worked or not