Okay. I've figured out this much: the stats hack is pointing to the standard version of public_common.pl. I'm using an HTML template, so the public_common.pl file I want to reference is actually in {noncgi}/templates/{html template name related to style}
I think the issue is that unlike all other sections in UBB, this does not have a "HTML Template" option. But before I go dig deep into this code and spend hours making it work, does anyone have the fix ready... err... already!