OK here's how I've worked out to do it - not quite satisfactory, but it will do for me:
tell application "/Users/me/Applications (Parallels)/{<some-guid>} Applications.localized/Microsoft Outlook.app" to activate
where the above path (including <some-guid>
) comes from manually launching the app, then right-clicking it in the dock > Options > Show In Finder. Obviously not a solution that will generalise to other users/other machines.
I'd still like to know how to get the application id and/or bundle identifier for a Parallels application, so I could use that as the argument instead of the posix path.