forcing charset of certain URLs

[jidanni@xxxxxxxxxxx]

This document
  W3m-current-url: http://localhost:8080/index/lasttime?sort=mtime
  W3m-document-charset: US-ASCII
  HTTP/1.0 200 WWWOFFLE Index
  Server: WWWOFFLE/2.9d
  Content-type: text/html
does not have a character set, and there is no facility in WWWOFFLE
(CensorHeader or not, right way to do things or not) to make it have a
character set, so in each browser one must figure out a way to make
sure the character set is not guessed wrong, e.g., one polluting
character and today emacs-w3m guesses wrong (can't blame it).

So I have to use
  C c runs the command w3m-redisplay-with-charset
by hand each time to make it utf-8, despite
my http://jidanni.org/comp/configuration/.emacs-w3m stuff.

I read up on `w3m-content-type-alist' but it seems too complicated to
understand. All I want to here in emacs-w3m is: for any URL matching
http://localhost:8080/*, make its "Document Charset" utf-8.