You can try contacting them through the help console and see if you get a response. Several years ago when I started with Custom Search Engines, I sent in a similar request; I outlined exactly what I wanted to do as far as font, colors and sizes. They sent me back an email giving me permission to do this (but noted on it that at the time it was a "special dispensation" kind of thing, and was not meant to construe that anyone else could do the same thing without asking first) I've always kept that email, just in case.
Yes, I've had some "special access" to a few AdSense things as well but just don't expect it to keep working as AdSense evolves. You wake up one morning and it's just gone, POOF!, and all that work around your "special thing" was a wasted effort.
Since then I try to work within their constraints just to avoid future pain.