preselectors?

http://www.w3.org/WAI/WCAG20/quickref/
http://ourmoneytoo.org/adjust.php
http://www.afb.org/myAFBcolors.asp

Each of these is a "preselector" for an accompanying Website. I am wondering
if it's feasible to build a generic preselector that, by looking into the
source and its style sheet, DOM, etc. could be applied to many (any?) sites?

I realize that proposing this makes me subject to being assigned an action
item, but I'm so far removed from the coding world that I thought I'd just
ask if anyone has thought much about this?

Love.