Under the Install/Uninstall options of an MSI package, you can specify logging options. Fill in a file name and tick the Logging Options checkbox. You'll need to enable the use of MSIexec at the top of that window, if you haven't already.
In the command line box at the bottom, you may wish to change the /log to a /lv if you want more verbose logging.
Thank you, precisely what I was looking for. Now if I could just make more sense of the LANDeks install logs...