By default, cPanel supports the usage of one dedicated IP per account. However, you can get around this by editing just a few files on the server. Here are the steps:
1. Edit /var/cpanel/userdata/$user/$subdomain.$maindomain for each subdomain (for addon domains you’ll usually edit the file for the subdomain associated with the addondomain) and change the ip value to a ‘dedicated’ ip.
2. Delete the associated .cache file for the file you just edited
3. Run /scripts/rebuildhttpdconf
4. Edit the dns zone for the subdomain (which will likely be attached to the parent domain) and update the a-record to point to that IP as well. Then syncronize the zone out to the DNS cluster, if one exists:
/scripts/dnscluster synczone <parentdomain>
5. Edit /etc/domainips and add an entry for that sudomain to point to the IP and run /scripts/rebuildippool to make sure the IP is marked as taken.