Example of using Apache mod_ext_filter to replacing urls in proxied data (phpundercontrol).

apache-extfilter.conf

<VirtualHost *:80>
  ServerName phpuc.dev.example.com

  # NB! It must be slow :-)
  ExtFilterDefine fixurls mode=output intype=text/html \
    cmd="/bin/sed \
      -e s/http:\\/\\/localhost:/http:\\/\\/phpuc.dev.example.com:/g \
      -e s/\\/phpundercontrol\\//\\//g \
      -e s/\\/cruisecontrol\\/artifacts\\//\\/artifacts\\//g \
      -e s/\\/cruisecontrol\\/logs\\//\\/logs\\//g \
    "
  SetOutputFilter fixurls

  ProxyPass / http://localhost:8080/phpundercontrol/
  ProxyPassReverse / http://localhost:8080/phpundercontrol/
</VirtualHost>