Hair pinning with pf and NetBSD

[buhrow%lothlorien.nfbcal.org@localhost (Brian Buhrow)]

        Hello.  I have a situation where a customer wants to talk from a box
on a private network to a box on the same private network, but using the
other box's external IP address. this network  is behind a pf nat NetBSD
box, which, according to the manual, can't send a packet to an interface
from whence it came.  The customer claims that every other firewall he's
used allows this.  Does anyone know of a way to simulate this, or to know
how to get it to work after all?
I'm using NetBSD-4.x.

-thanks
-Brian