Join Date:Joined: Jan 2011
You can't prevent installation. You could put a check at app initialization that causes the app to exit immediately, by checking something like the MaxUnsignedApp registry value, but reading the registry isn't officially supported so a Store app doing it would probably be blocked.
It's a pretty pointless thing to check for anyhow; anybody who wants to could decompile the app, figure out the check, and work around it (for example, by temporarily dropping interop-unlock when the app starts). Jailbreak detection is, and always has been, a lost cause and a waste of effort.