[Zope-PTK] Replacing Icons for standard content types

[Lucas Hofman]

What would be the 'best' way to change the icons for the standard
content types like document, link, file  etc.?

As far as I can see are these defined by the call to
registerportalContent:
registerPortalContent(News,
                      constructors=(addNewsItem,),
                      action='Wizards/NewsItem',
                      icon="newsitem.gif",
                      productGlobals=globals())

The link generated by 
<img src="&dtml-portal_url;/<dtml-var expr="obj.getIcon()">"
evaluated to:
<img
src="http://tanya.oslo.seres.pgs.com:8080/seres/misc_/PTK/News%20Item"

Zope finds this in PTKDemo, and not in the custom skin directory. 

How can I change the icon for 'News Item' without replacing newsitem.gif
in PTKDemo? (which makes updating difficult). Do I have to make a new
class just to change the Icon?

Any help is very welcome.
-- 
Lucas Hofman
PGS Seres                                        tel: +47 67514059
PO Box 354                                       fax: +47 67526640
N-1324 Lysaker, Norway