[Mediawiki-l] .htaccess/rewrite help for subdomain

[Michelle]

I managed to get .htaccess Rewrite to work and yield pretty URL's for  
a basic setup like this:

www.mydomain.com/wiki/index.php/Main_Page

The wiki is installed in w/ and the pages show the user the nice  
wiki/ URL's.

Now I'd like to change the external URL to my wiki to be:

wiki.mydomain.com/index.php/Main_Page

Where wiki is an empty directory because the wiki code is still in w/

Some noob questions:

Does the .htaccess file need to be in the wiki directory rather than  
the root directory? I assume so since it's like a different site. I  
can't seem to get it to recognize where the w/ directory is. For  
example, this htaccess in the wiki directory yields the correct URL  
but a 404 error on the wiki:

RewriteRule ^index.php/(.*)$ /w/index.php?title=$1 [L,QSA]

I've tried more explicitly specifying the 'to' rule but it just  
yields a mess.  If I move .htaccess up one level to the domain.com/  
root, then it seems the rules don't recognize that wiki.domain.com is  
valid.

So if anyone has made the pretty URL rewrite rules work for a  
subdomain, I'd appreciate knowing what you did.

Michelle