1. Install PS3 Proxy server, and START it up.
2. On the PS3, Network Settings, choose use proxy server and enter the IP of your PC (I'm using to connect to directly connect to my PC a crossover network cable, nu router or anything and using static IP's on my PC).
3. Startup the ProxyServerGui, entering you IP address and selecting PS3 mode.
4. Capture the link of Folding@Home (try to download from your PS3, watch the ProxyServerGui LOGS tab than cancel the download).
5. On the Replace files enter a new line add the proxy server addres and to the files add any demo you have on you PC (you know, the PKG files).
6. Download Folding@Home again, this time it will be replaced by the chosen Demo.
That's it. So you can install any Demo without Internet, with a direct connection over a crossover link between your PC and PS3. As I had mentioned above: I'm using firmware 1.70. Don't know if it works with 1.60.