Yes, with one caveat: the popup UI is dynamically generated from the
services array, so will be messed up unless you also modify "popup.js"
(to gracefully render or just ignore the services you've added). You
only have to fill the first two elements of the array in to block
third parties (the order of the domains in the second element doesn't
matter, although by convention, I put the organization's primary
domain up front).
> If so, is there an easy way to collect the different path names they phone
> home with?
No, but lots of folks have already done the collecting. For instance,
see the EasyPrivacy list for Adblock Plus:
http://easylist.adblockplus.org/en/.