Restoring Lion/iCloud iCal from Time Machine
From what I can tell, Time Machine doesn't allow you to restore iCal calendars through the iCal app. And actually, you should be able to restore that calendars folder. 

While the directory contents are complicated, iCal should translate them back to what you had before. The only other thing I would bring over just to be on the safe side is your iCal's list file, located in ~/Library/Preferences. It should be called com.apple.iCal.plist. I would recommend moving this from your Time Machine backup to the same directory on your Mac. 

That should do it for you.