MAC cloning available like Linux has?

[Chris H]

Greetings,
 I attempted another BSD install on another piece of hardware the
other day. I'm evaluating a different ISP, and the gateway/router/modem
they provided, has 1 ether, which I currently use on my server, and 1
USB(3) port that I had intended to use with the new install. Problem I
ran into, was that BSD generates random (fake) MAC(3) addresses, when
utilizing the CDCE(4)/ue0. This worked just fine during the install.
But the modem "held" the MAC(3) generated during the install, and I
now have no idea how to tell BSD to use that MAC(3) when negotiating
with the modem. I had absolutely no difficulty assigning the MAC(3)
address when spinning up several "live" Linux distro(s) -- they provide
the following:
su
password: ***
ifconfig eth1 down
ifconfig eth0 hw ether ##:##:##:##:##:##
dhclient eth0
blah, blah, blah

And I'm connected.
Couldn't manage that with BSD. What must I do? Is it even possible?
If so, can it be assigned for use on a permanent basis?

Thank you for all your time, and consideration.

--Chris