Hmm, got me stumped on this one.
Why is it required? You could end up spending a lot of time sorting this out, so you need to be 100% sure it is required, and worth your time.
Off the top of my head, how about disabling, or switching off, the modem and leaving the service on?
It might be worth doing some testing. As a rule, if you can do it in the GUI, there is normally a way to do it in the command-line, which means you should be able to script it.