[exim] DNS Question - Advanced

I'm starting my own dns blacklist and real close to getting it working.
I have a quick question.

My domain junkemailfilter.com has 3 name servers set. But - for the host
dnsbl.junkemailfilter.com I'm using a different nameserver. So I want to
tell that world that a query to 92.239.252.87.dnsbl.junkemailfilter.com
should go to this new nameserver instead of the regular one for the rest
of the domain.

How do I do that?

And - I will let others use this once it's working.

Thanks in advance.