One quick and easy way is to make a strip of alpha color.  Then, split it up
by the width of each frame.  For example, if I have 4 images in an animation
loop, each 64 x 64, I'd need a strip 64 pixels high and 256 pixels wide.
Then, draw a fram of animation in each cel.
When you load in the strip file, you can either slice it up now (I'd suggest
Numeric) and put each slice into a list, or you can use a viewport technique
later.  I'd suggest slicing it now, as I believe it's cheaper on processing
in the long run.  Now, you can on the sprite's update set self.image =
strip[i], where i is the current index.  It's recommended to put a delay of
a few cycles between each increment.

Ta,

-- 
Andrew Ulysses Baker
"failrate"