Howto set DHCP_HOSTNAME?

[Neal Becker <ndbecker2 gmail com>]

I've been using nm with Fedora (now FC6) with good results.  I just had to
buy a new usb enet if, because eth0 has died.  nm brings it up OK, but
without DHCP_HOSTNAME.

In /etc/sysconfig/network-scripts/, I have:
ifcfg-eth2.bak
which includes the DHCP_HOSTNAME line I had manually added, and I have:
ifcfg-eth2, which nm made, which does not have DHCP_HOSTNAME.

How do I convince nm to include DHCP_HOSTNAME?