This has nothing to do with any styles.
Before you can use this, you must have a domain name or subdomain configured pointing at the same web space as your primary domain. Usually a CNAME record for teh secondary [sub]domain pointing at your primary domain will do the trick - check with your provider if you don;t know how to do this.
Additionally you will need a secondary style installed.
Instructions:
- Save XML file in first post to your computer
- Log into AdminCP on your site
- AdminCP -> In Plugins & Products -> Manage Products click the [Add/Import Product] link at the bottom of the page
- Click the Browse button and locate the XML file you saved to your computer.
- Click the "Yes" radio button to allow overwrite
- Click the Import button to import the product.
- Now go to AdminCP->vBulletin Options->vBulletin Options
- Locate the "Different Domain, Different Style" section.
- Select 'Yes' to enable DDDS
- Enter in the [sub]domainname you wish to specify a style for. eg. mobile.vbulletin.com
- Select the style you wish to use for this domain name.
- Click the "Save"button.
- Now go to AdminCP->vBulletin Options-> General Settings and add your [sub]domain name to the Post Referrer Whitelist
Assuming all is configured correctly (style, [sub]domain and this add-on, you should be able to browse to your [sub]domain and get teh configured style.