[plt-scheme] cookies in plt web server

I understand that one can set cookies in the plt web-server using
"extras" in make-response/full, but that seems to be as far as the
documentation goes.  Does anyone have an example of setting and
reading cookies that they would pass along?

Also, I found some code "cookie-unit.ss" on the plt site that provides
a nice interface for creating cookie structs, but it's a few years old
and I'm not sure what kind of shape it's in or how it plays with the
plt server.  Does anyone have any experience using it?

PS, I know cookies are evil, but sometimes they're a necessary evil.