Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
You have to start from the top and exclude about 10 folders (System, Library, etc..) or so to get what you want to backup.

Unfortunately, there isn't a way to select what you want backed up; you have to pick what you DON'T want backed up.
 
Isnt there a third-party app that lets you mess around with time machine preferences, like to set the time intervals and such? Timemachine edit or something like that? Maybe that one just lets you edit the times I'm not too sure but maybe search around, they may have created another third party app that might help you.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.