Guestbook on Google Sites

Since the opening of sites.google.com, I have been trying on everything to transfer all of my hobby projects (mostly wikis) to this engine. But there remains only one problem: how to organize a simple guestbook there. I looked for gadgets, found only scary poor chats working in a small window with a bunch of scrolling bars ... At one time on WackoWiki, it was enough to make an action on several lines that changes the sorting in the regular comments on the page and adds scrolling through several dozens.

Who will tell you in which direction to dig to create the simplest guest as much as possible natively looking for Google Sites?

Of the other minuses noted, the engine can be noted not the possibility of using your domain. Only for the redirect to sites.google.com/a/VASH_DOMEN_BUDET_VIDEN_TUT/NAME_SITE/ but this little things can be put up with.