I used this page, it has the perfect tools listed for the whole process.
Outworldz
The tool GIF 2 SL Animated Texture Program for Windows is perfect. Small and fast. Found at:
http://www.outworldz.com/Secondlife/Posts/gif/Create-Gif-in-Second-Life.htm
Saves you a lot of tiling in photoshop or gimp.
Here's the script that goes with it.
MultiGIF_menu_1.lsl
http://www.outworldz.com/cgi/freescripts.plx?ID=535
Personally, i use the tool from ezgif to edit the gifs, or even make some. they have an excellent file deletion policy.
http://ezgif.com/
Good luck with that!