Alias and other forms of Alias on an Unix with Apache

Ok, I'm trying to setup an affiliate program, whereby, their is NO affiliate id in the url or something like that.

It will work like this:

the big affiliates get their own domain, their domain name is their affiliate id.
The smaller ones SHARE a domain and get a subdirectory.
The subdirectory is their Affiliate ID.

I'm trying to use Alias in httpd.conf to accomplish this.
I'm using PHP as the scripts, so it would then take the URL called,
and check it for the affiliate ID. If it contains a subdirectory, then
the Subdirectory will be the affiliate ID, otherwise the domain is, as stated above.

Using Alias I should not have to actually create different subdomains, as it
should just forward them to the main script.

Here is what I've tried:
<VirtualHost 0.00.000.00>
   ServerName somedomain.com
   DocumentRoot /home/user/www
       Alias /* /home/user/www
</VirtualHost>

AND I've also tried this:

<VirtualHost 0.0.0.0>
   ServerName somedomain.com
   DocumentRoot /home/user/www
       Alias /* "/home/user/www/"
   <Directory "/home/user/www/">
       Options Indexes MultiViews
       AllowOverride None
       Order allow,deny
       Allow from all
   </Directory>
</VirtualHost>

None of those worked.
How can I get it to take ANY subdirectory called, and
send them to the www directory? I thought * would act
as a wildcard, but it's not working. I get a 404 error.

Any pointers would be most welcome!

If you need further clarification, let me know.
Thank you.
Richard