Installing .NET Framework 4 on a computer not on the internet

I have a computer running XP Service Pack 3 at home, but it does not have internet access. I've been using a flash drive to transfer software from a public computer to my home computer, but I'm having a hard time with Framework.  Every time I try to get Framework onto the flash drive, I get a message that says I need an administrator account to finish downloading Framework. Naturally, I don't have such access on public computers, and I have no idea how to get the update from there to my flash drive so I can put it on my computer. Please help!