nameservers for resellers/clients ?

[JohnB@]

Hello:

We are planning to transfer a few reseller accounts from another older server to a new powerful server.

PROBLEM: the current new server and the old server use different nameservers -- such as:
(a) ns1.server.net / ns2.server.net
(b) ns1.server.com / ns2.server.com

Is there a way to keep the existing nameservers (and change IPs, of course) for the domains from the old server after transfer? Can I set the transferred reseller accounts up with their old existing nameservers on the new server?

If so I'd be grateful for a step-by-step HOW-TO.

Thanks,
John