How Do I Adjust the Frequency of Time Machine Back Ups?

You can't , but you can turn off TM in system preferences and choose "run back up now " from the menu bar when you want to back up.

Yes. Go to User Name>Library>Preferences. Locate the Time Machine preference file (a file with the word TimeMachine as part of the name). Open it in TextEdit. Look for the number 3600. This is the amount of seconds for the backup to start. The default setting is 1 hour, which translates to 3600 seconds. If you want to change it to each day or week just change the number (in seconds) that's equivalent to the amount of time you want. Save it and that's it.

PS: If you want to make a backup of that file first before changing it you can do that. Copy and paste that file onto the desktop and should you make an error or decided to go back you can always put the original file back.

Commonman,

There is an application called Time Machine Editor, you can easily customize the frequency of your TM Backups. Here is the URL for it:

http://timesoftware.free.fr/timemachineeditor/