Thanks for reply but it doesn't. It's
saying something failed to enforce SSL
requirement on IIS. VSS web services
would be disabled on this machine....
I had the same problem with the VSS internet plugin, turned out that my certificate was installed/trusted in my personal store and not the local computer store. When VSS attempts to set this up it attempts to contact "https://servernamethatyouspecify" as the local system account. In my case I was using a self-signed certificate that was not installed/trusted in the local computer store but instead just the personal store of my user account so this request would fail with the security warning saying that this certificate is not trusted.
To make a long story short, just reinstall your certificate but specify the option to 'show physical stores' and be sure you import it into the "Trusted Root Certificates" -> "Local Computer" store.
Overall VSS is a pain to configure/setup, especially the internet plugin and definitely slow for large projects, however if its all you've got the internet plugin does work fine for small projects. I've used SourceOffSite and it worked pretty great while we had it, managing keys can be a pain but pretty easy to setup.
I'm sure you can use VSS over a VPN via file shares too but I'd imagine that'd be an even slower option with the overhead of using file shares over a vpn.
good luck!