All the themeblocks that you see to the left, right, on top (this block) and on bottom of the MAIN page block are controlled by a single 'Modules/Pictures/Pictures_custom.asp' file. You can show any themeblock that is available on the homepage here as well. Or you can create your own function. This way, people can change the layout to what they like, and also keeping their layout in a file that will not be included with future upgrades.
The subroutine for this block is called modFeatures() and is located in fp_custom.asp at the very bottom of the file. The call for this subroutine is called modFeatures() and is located in 'Modules/Pictures/Pictures_custom.asp'.