I can't see the problem. Open photoshop, load the few gifs that you used in the header, join them in a big GIF and put it in the header. Then you put an img src="mynewimage.gif" and that's all.
It's not so difficult. The header IMAGE, Title IMAGE or whatever you want to call it doesn't require any special php code.
It's just a matter of doing some copy&paste with your favourite paint package and put all the old gifs in a bigger one. Or if you prefer smaller gifs make a table with 3 cells and load 3 gifs separately...
There's no magic code in the header...