[Fwd: Upgrading from Core1 to Core2]

I received the below message today. Does anyone have any docs on how to do this? Thanks, Tammy -----Forwarded Message----- Since Core1 is EOL, I would like to upgrade to Core2. I have thousands of core1 devices all over the world. All of which I do not have physical access to. I only have SSH access to these machines, and it seems that there is a severe lack of documentation on the subject of upgrading core1 to core2 remotely over ssh without the use of serial or net booting. Unfortunately, this puts me in quite a predicament, and I would be eternally grateful if you could point me in the right direction.