Being that I hate every hour backups (well, not the backups, but I hate the volume level of my external drive), and I’m fine with a backup running once a day – here’s how to set Time Machine with a custom interval:
1) In the Time Machine preferences, turn it OFF
2) (We’re built on Unix, yea?) Set up a cron to run backupd-helper (Which is equivilent to the ‘back up now’ selection when you control-click the dock icon)… If ‘crontab -e’, and the vi editor are foreign to you, I’d probably stop, or do a ‘man 5 crontab’ or something from a terminal session. If not, here’s my daily 3am backup:
0 3 * * * /System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper
Every 2 hours, at 15 past the hour would be:
15 */2 * * * /System/Library/CoreServices/backupd.bundle/Contents/Resources/backupd-helper