The Dink Network

I'm trying to change the colours of Dink, something like Sid from Legend of Tenjin but I can't find a way to do it easily. I tried asking Wesley how he did it but can't get hold of him.

Any ideas how to go about it? I'm using the GIMP, but there must be a quicker/easier way than just painting new colours into every single frame...

I don't know about GIMP, but a picture's color can be changed by tinkering with its hue.

There is IrfanView