NOTE: I do not have physical access to the server mentioned in the following post. Is it possible to migrate from Redhat 9.0 to Fedora Core just via SSH?

possible, yes. Easy no.

In order to do it, you pretty much have to set up a seperate partitian, make it into the filesystem of your choice, manually copy over the fedora files, set up a bootstrap, change your bootloader and cross your fingers and hope you didn't screw anything up. It's pretty much the same process used to set up gentoo, except without the compiling.