There are some tutorials below, will it working for parked domain, or only for addon & subdomain?
http://www.ndimensionz.com/kb/dedicated-ip-to-parked-addon-domain-in-cpanel/
http://www.prajith.in/how-to-assign-a-dedicated-ip-to-a-sub-domain-or-add-onpark-domain/
http://thelinuxfaq.com/183-assign-dedicated-ip-to-subdomain-parked-domain-addon-domain-in-whm

there is also a thread asking this in 2008 https://forums.cpanel.net/threads/parked-domain-on-different-ip-address.93537/#post-424165 :
The main domain does have its own IP Address, but I need the domain that is parked on the main domain to also have its own IP Address. So for a example:

Main Domain: brad.com
Main IP: 64.64.64.64
Parked Domain: steph.com
Parked IP: 64.64.64.64

Needs to be

Main Domain: brad.com
Main IP: 64.64.64.64
Parked Domain: steph.com
Parked IP: 35.35.35.35

its says not possible that time, is it already possible right now? i need it if possible

Have you communicated with your domain registrar about this?

its nothing to do with domain registrar, only in server/cpanel