You have to do a redirect in you .htaccess file.
Here is the code I used to redirect.
Redirect 301 12.12.123.456/ [widgets.com...]
Options +FollowSymlinks
RewriteEngine on
RewriteCond %{HTTP_HOST}!^www\.widgets\.com
RewriteRule ^(.*)$ [widgets.com...] [R=permanent,L]
Obviously you have to put your info in place of the ip address and domain name.
It took them about one month to finally make the change. In the meantime they will probably remove all of your pages from the index.
Good luck.
I'm far from an expert in this area. I was here asking the same questions about 2 months ago when I had the same problem.
I would ask the host about it. Alternatively, you could post this question in the Apache forum at [webmasterworld.com...]
They should be able to answer your question there.