Actually,
It's in the uImage/kernel .
There's a thread somewhere on the Hyves trendtac board, or was it here?
I don't remember now, but it was about dismantling the kernel, changing the image with your custom one & and putting it back together, then when you flash it to the machine, the boot picture will change.
That's why the newer kernels from CnM say CnM book @ boot, Elonex says Elonex.. etc