iPhone Any way to downgrade first gen iPhone to iOS 1.0?

Hi there
I recently came to acquire an original first gen iPhone currently running 3.1.3. For nostalgia and fun's sake, I'd love to find a way to downgrade this back to the original "iPhone OS" (as it used to be called) version 1.0. I've got the IPSW file, but I've read it's virtually impossible to downgrade without the original SHSH "blobs." Am I 100% stuck or is there another way?

Holy crap, that link looks promising. It's gonna take a bit of work (PITA to get Windows XP on my Mac), but I'll give it a go! Thanks!

I'm so close but can't seal the deal. I got 1.0 loaded on but it's stuck at the damn activation screen (bc obviously Apple isn't activating that OS anymore. There were instructions to install a software activator, but can't get it to work! Damn!