Cheers! There are no .fss files available on the internet - using them was just a stopgap measure to test the progress of emulator before adding disk support. The easiest way create an .fss is to download Frodo for PC/Mac (e.g. from here) and hit Ctrl-F9 (I think) when your game is running.
I was just playing round with analog stick support yesterday. I'm mulling over disk image support right now though.