The best way to do something like that would be to arrange your graphics in one long strip, for example if you needed to load 10 images and they were 100 X 100, you could arrange them so that they were placed side by side to create an image that was 1000 X 100 and you could grab the 10 frames of animation using a for next loop, have an x co-ordinate and increase it by the width of the image you are taking each frame.
I think that the get function in gfxlib would let you do this quite ok, unless you are using tinyptc which is a little bit more tricky, rbraz made some nice tools to load 256 colour bitmaps.
http://dbfinteractive.com/index.php?topic=370.0If you are using tinyptc and need some help on this I will write more if you're stuck because I use this for loading my pictures no problems.
The other option is to use Thrawn's png lib, load your image with it and then cut the bits out that you want.
Edit - Fixed link formatting