Just wanted to confirm what's described on this troubleshooting page (http://www.retrode.org/documentation/troubleshooting/troubleshooting-saving-files-to-the-retrode-does-not-work/) and make it clear that this technique of overwriting or saving files back to the Retrode DOES work for Mac users (since I am a dummy and didn't see "Mac" on the page so I thought I was SOL).
First, I copied the config file to my Desktop, opened it in TextEdit and changed [saveReadonly] 1 to [saveReadonly] 0
Then, went to Terminal, typed the following
cat /path/to/modified/RETRODE.CFG > /media/RETRODE/RETRODE.CFG
Replacing "/path/to/modified" and "/media" with my actual paths. For me it was:
cat Desktop/RETRODE.CFG > /Volumes/RETRODE/RETRODE.CFG
This technique also worked for me instead of dragging and dropping savegame files to replace them. For example:
cat Desktop/PokemonSnap.NPFE.fla > /Volumes/RETRODE/PokemonSnap.NPFE.fla
Anyway, hope that helps another non-savvy Mac Retrode user!