Custom Root Category Image

[amgadhs]

Hi,

I'm creating a restaurant directory and have 2 main categories in Root: By Type, which has sub categories like American, Chinese, Italian ... etc, and By Location, which lists the main areas in the city. I want to keep the category icon size for all categories 32 x 32 or 48 x 48 but want to use 2 large images for the first to categories, most probably 100 x 250 pixels.

So my question is how could I customize the Root category to display a different icon size or customize the homepage to show these large images instead of the default category view?

Thanks