[Zope] specializing folders

[Dennis Allison]

I have a portion of a site which originally consisted of a single folder
with content.  In the reorganized site, this folder consists of a
collection of folders. For specificity, the structure looks like

     +--A--+--A1
	   |
           +--A2
           |
           +--A3
	   |

Depending upon a parameter derivable from the HTTP_HOST name, I want 
either A1, A2, A3, or ... to behave as if it were A to all the other 
code in the site.  Of course, A1,A2,... should be able to hold code and/or
data.  

I would have though that some sort of local use of a VHM and or SiteAccess
would allow this, but I've been unable to make it work.  Any suggestions?
hints?