First, the Sony Support site SUCKS!!!!
I found one place on the web that said that the restore disk would work with an external CD-ROM as long as it is a Sony CD-ROM, but it wasn't an official site. Whoever designed the site couldn't spell very well, so I'm looking for som corroborating evidence. I have a Sony External ROM, but I'm concerned as to whether or not this guy knows what he is talking about.
Another option on that same site was to copy the System Recovery Disk to the HD and restore from there, but how is that possible since one of the first things the Restore Disk does is wipe the HD?