A Nexcess account on a physical (non-cloud) server and access to SiteWorx; If you use Nexcess Cloud, see instead What are Nexcess Cloud dev sites? for details
Using SSH or SFTP, copy your website files from your PHP installation to your new secondary domain. SSH is the preferred method, as FTP may take considerable time to copy these files. See How to transfer files to a server with SFTP for details.
Change the base URL by opening your newly imported database in PhpMyAdmin, or by accessing via CLI. In the core_config_data table, update the web/unsecure/base_url and web/secure/base_url entries with the URL of your dev site. See How to change Magento URLs for more information.
Verify you have updated all URLs by searching for %%, and update as necessary.
Using a text editor, modify your app/etc/local.xml file to the new database name, mysql user, and password you made in Step 4. Save changes on the files you copied to your new dev site.