You can access your FTP accounts without having a domain name pointed at the site by using the Instant Alias hostname.
In order to find the Instant Alias hostname do the following:
- Login to your hosting control panel.
- Click Domains.
- Click the Domain you want the Instant Alias for.
- Its shown under Instant Alias. If its not created you can click the option to create one.
- Use that Instant Alias as your FTP server address in your FTP software.