Other Options

There are none. The phone needs to be able to check with the Apple servers to make sure it has not been locked. This will require an internet connection either through a cellular connection or WiFi.

Do you have a question? The requirements seem pretty clear to me. Connect to a computer or to WiFi service. I am guessing "activation" is referring to setting up cellular service, so that obviously won't be an option because that is what you are trying to achieve.