LiveCode Player R9 has no listed command line options, and it's a nasty Flash-looking custom GUI installer. However, the developer site has documentation on how to install the LiveCode developer environment from the command line, and it turns out some of the same arguments work with the player as well.
This worked well for me:
LiveCodePlayer-R9.exe install noui -allusers
It may be necessary to run that command in a "start /wait" shell, as the install doesn't seem to properly return control when it's finished. Eeeeesh.
Using these options, the thing installs a RunRev directory in C:\Windows\System32; there's a setup.txt file a couple levels deeper that has full registry and file changes listed (plenty of stuff to make a custom inventory rule from).
Here's the release notes for the full developer version -- there are more switches there, but I didn't need/care to try them: