Above was the short answer, to a question like "can I drop this Dodge Viper engine into my Honda?".
BTW, your Jukebox display is not even grayscale, it's b&w.
Long answer is you could hook up a different display, if it has an SPI interface and internal frame memory. But this is only for the micromechanically skilled, don't expect anything close to a matching connector or a mechanical fit.
Plus, it would require quite some software rework on Rockbox, to adapt it in general, and then to bring in color. The Archos software would be "blind", not using it. A grayscale or color display would be substantially slower, because of the incresed amount of data to transfer.
The way you asked makes me think you're not up to the task, no offense.
Jörg