Here’s a way to quickly setup a bunch of domains on an IP range:

1. Navigate to Admin UI > System > Domain Conf page
2. Hit the “IP Ranges” tab
3. Click “dc_create” on the free range you want to employ
4. Paste a bunch of domains and click “Create”
5. Click “Save configuration” at the bottom
6. Click “Apply all changes” at the top

Make sure to point your domains and have rdns setup, as per the “[r]dns” file found on the “Configurations” tab. Easy peasy.