Background image fading rotation effect

Hello all,

I'm currently doing a design that has transparent pngs and the idea was to have a rotating tiled image in the background. Something simple like a blue, green and red tile all fading in a loop. Also I'd need to set how quick it happens.

I've seen some javascript image fade rotators but nothing for the background.

If this isn't possible then is it possible to do the same fade but with just the background colour?

Any help would be great.

Thanks Sul...