save your image as a .png but make the filename say filename.gif or whatever.gif. FA gets confused with the filetypes, presto you have an anti-aliased icon :D
But.. That isn't real antialiasing! It looks really good though. I guess you have to go for a real neutral colour for an outline. It looks alright under FA's dark theme.
YOU PRESS F5.
(I like the new avatar 8D)
Or really obvious hint.
FA just mangles it in the process
just name your alpha-channel'd PNGs as GIF files and there you go
Gotta wonder just how secure the site is.
Not much, but this is to upload art, not to handle banking transactions. ;)