Nope, sorry!
No,
There is no way that I know of using Time Machine editor (or any other external tool) with local snapshots. Time Machine needs to be turned on in order to create the local timeshots, and it does this as one job.
It actually creates local snapshots (as disk space allows) while doing the hourly backup. If you're not connected to a network or your back up disk, then it will just run a snapshot locally. But Time Machine must be turned on.
Another reason that I have stopped using TimeMachine Editor is that it does not have an option to respect battery power. Time Machine does, and so it will not backup automatically if I am not connect to mains power.
Have you tried the option with the Plist file? (But once again, even if it works you will only get local snapshots at the new interval you set). I did try once with Snow Leopard over a year ago with the Plist option, but never got it to work.
I would be very happy with 3 hourly backups!!!
Long and short, I don't think there is a solution, and this is an example of Apple Culture in not providing more comprehensive options (which in the bigger picture is actually good, but frustrating when using a slower machine over a wireless network every hour).
Sorry, I can't really help!