It would be impossible without massive loss of quality, GIF only allows dithering of up to 256 colors (excluding transparency.) You might be able to fit them altogether but the filesize would be massive and the quality would make them almost unrecognizable. APNG would make the filesize loving huge with little to no loss of quality, but Chrome, IE, and Safari users wouldn't be able to see the animation without a plugin. Good luck finding anyone to do this for you.