I'm working on a scripted install of something, and one of the parts is adding an Apache Bigtop repo and installing things from it. But having to do an apt-get update before installing is quite time consuming because of all of the other mirrors touched (and I do an update before hand to make sure the system has previously used tools in the script). Is there either a way to do an update that doesn't update everything or a way to do an install and specify a repo/list that hasn't been updated?