I will try compiling a (network only) version of the emptool library some day in the near future. I will tell you if it worked out well.
However, I already dug in emptools sources for a while, and it seems as if that ReadFidToMemory is just the function we are looking for. PLUS it seems to provide a way to backup any player configuration files (well those of the standard player at least), including identity, general and network setup. I really wonder why noone of those mighty programmers around here didn't go and try this out month ago. I hope I get it to work, but even if not, I think I will be able to create a empbackup/emprestore program set for linux at least.
I will take a deeper look at the emptool sources during the weekend, and hope to be able to tell more by monday.