Network interface failover in 6.2?

I need to set up a simple NIC failover in a 6.2 host, connected to Cisco
2950 switches. From searching the web it seems that the simples option
for me is to use ng_fec (I'd rather use trunk/lagg, but I can't use
-current for this). Since I haven't used netgraph before, I'd appreciate
any advices and caveats (especially: is anyone using this in production?).

From documentation and examples found on the web it looks like I need to
do this:

ngctl mkpeer fec dummy fec
ngctl msg fec0: add_iface '"em0"'
ngctl msg fec0: add_iface '"em1"'
ifconfig fec0 up
ifconfig fec0 inet x netmask y

Is this correct / all?

I also found a pointer to use ng_one2many but a) ng_fec is supposed to
make use of the router's support (FEC), and b) it looks more complicated
to configure.

What is the practical meaning / difference between mode_mac and
mode_inet in ng_fec?

One other thing: where should I add the above configuration? In
/etc/rc.local?

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