help on dns configuration for mapping under cpanel. Becoming crazy !

Well I feel stupid...

But cannot manage to set this up and even dont know if it is possible.

Here is my point :

I have a dedicated under Cpanel with several multisite installs, with domain mapping offered.

I would like to be able to sell custumers domain names for them to map on their blog.
BUT that supposes to create a new cpanel account for them to create their mail adresses for example.

Problem : the account is on the same server. SO how can they setup their domain to point on their blog ???

They can use simple dns editor for aname and cname but of course in this case the domain cannot be "parked" on the main install.

so, what is to setup to point domain1.com on blog.domain2.com on the same server/ip ?

By default, cpanl creates a cname on the concerned domain on www , and a A record on the server ip.
Those cannot be changed by the user directly of course.

Is it just possible ?
Shall I buy another IP adress, set it up on the server as default for new accounts, and the add a A record on the other ip ???