I see and completely understand the need for having, let's say, a decentralized (from the Iranian) Internet. However, this requires resources, time and most likely money. I don't think you will be able to bypass/piggyback the Iranian Intranet or their Internet firewall, it will also make it easier for the Iranian government to track you if you try. The way I see it is trying to find your own Internet access. That sounds easy, but I can definitely see it not being the case. Maybe through satellite, maybe someone living close to a border and being able to use an Internet line from the neighboring country, there are more possibilities, I'm sure, but these come into my mind at the moment.
Let's say you manage to get independent Internet access, now you will have to find a way to get this Internet to all the people that want to use it, setting up the necessary network for that and keeping it hidden is another major task, will you risk using WiFi? If not, how will you get cable to necessary hubs? Can you trust all the people involved in setting this up or will someone inform the government because they love the current regime so much?
That being said, I'm sure that with enough money, motivation and maybe mobilization of help from people you can trust it is in theory, difficult, but doable.