The interface # for his wired card is probably different than yours.
So in the format of this command
route change 10.10.10.0 mask 255.255.255.0 10.10.10.250 metric 5 IF 20
IF 20, is specifying interface 20 for the route.
Do a route print on his machine, look for the Interface list at the top, find the wired card and I bet it isn't 20. Try the command again(don't use -p until you know it works, that way you can just restart the computer to clear it) using the correct interface number.
Ok so I checked and the interface is indeed 20. Any other thoughts? I am also curious what the "metric 5" does, because it's not setting the metric at 5 obviously...