Custom skin assignment?

[Chris 96 WS6]

I've added a mobile skin for my forum, for people browsing by phone/pda, etc.

I am using this mod, but its not always easy to get it working with every device type.

So I'd like to also have a subdomain like mobile.myforums.com and have that subdomain redirect you to the forum home with the mobile style selected.

So right now I just have an .htaccess redirect in the /mobile folder that redirects the user to www.myforums.com/forum/index.php?styleid=5.

But it is only displaying the mobile skin if you are already logged in. As an unlogged in user you get the default skin. So clearly this has something to do with sessions, but I'm not sure what other steps I need to do to give an unlogged user the correct skin.

Any ideas?