I'm using an Intel 82559 ethernet adapter and I want to get it into promiscuous mode to monitor traffic.

The adapter has been working for me fine, and I can do things like change the ip address with commands such as:
ifconfig en0 192.168.1.10

Pinging other devices on the network works fine, and directed traffic works fine.

However, I've been trying to put the adapter into promiscuous mode, and it seems that I need to do it when loading the 
driver. I'm not sure if there's a boot script somewhere that is doing that already (I haven't been able to find it) but 
when I try the command:
io-pkt-v4 -d /lib/dll/devn-speedo.so promiscuous

and then run ifconfig en0 I get:
"ifconfig: SIOCGIFFLAGS en0: No such device or address" so somehow that command is destroying my ability to access en0 
and I can no longer do anything on the network.

I'm pretty lost as to what the problem is here, and I can't seem to find anyone else who has experienced this issue.