I have the REvit 2010 Trial installed on my computer. I can't find the Imperial Library. Just the Metric.
My administrator is away this week (when I'm supposed to be working on this) so I can't install anything off the disk if it's on there.
Naturally you can install these when you install Revit, the link I gave you says so right at the top, so the blame rests squarely with the installer. PEBKAC errors are always the worst.