If you try to rename the file, see if that works, don't expect anything since I have no clue if it will really work.
That wont work for sure. If Im not wrong, the save type of Gamefaqs is a
gameshark snapshot save file...(Example: GoldenSun2.sps) Theres no way to convert them into .sav. If you are using Visual Boy Advance,there is a way.. Follow this...File>Import>Gameshark Snapshot>[GoldenSun2.sps]. This will reset the emulator ofc but what was changed is your save file! The one that gamefaqs are storing their savegames! Have fun. ^_^
EDIT: Also if you want to donate your save file to gamefaqs, well you File>Export>GameSharkSnapshot. Give it a try.