Where do I put additional images?

I’m trying to add some additional content to the login page, which
includes a couple of extra images.

Where should I be putting these so that I can refer to them in my
modified login screen?

So far I have: local/html/Elements/Login with my changes in it.
So I put the images in local/html/NoAuth/images/xyz.png and then copied
the autohandler from share/html/NoAuth/images, just for luck,
and referred to it as NoAuth/images/xyz.png in my CSS. That doesn’t work
though, so it seems the usual RT overlay style of doing things is not
supported for images.

Where should they go? Last time I did this, I ended up with a little
non-RT-handled directory configured in Apache to serve my javascript and
images, but this time I’d like to figure out how to do it properly…
fishing through the RT codebase to find which parts I have changed is a

Also, is there any kind of guide to skinning, or otherwise fooling with
the CSS in RT?