You'd need some animation software to do so. I don't know what everyone here uses, but if you have Photoshop, there is software that comes with that called Image Ready, which makes animated gifs.

This is a good thread: http://forums.animesuki.com/showthre...42&mode=linear but their server seems to be down at the moment.

View this (Google cache page of it: http://216.239.53.104/search?q=cache:wTucA...&hl=en&ie=UTF-8 )
hope it works for you!