sending an arp...

I found an article on the net that clearly explains exactly what I'd
love to be able to do... Unfortunately, I can't get one critical part
of it to work: http://www.onlamp.com/pub/a/onlamp/2...inuxhacks.html

send_arp using the syntax on this website fails. If I modify it to

send_arp eth0:1 123.123.123.12 00:C0:9F:14:82:3F 123.123.123.12
fffffffffff

(123.123.123.12 is the IP address of the website I'm taking over which
is binded to eth0:1 and 00:C0:9F:14:82:3F is the MAC address of the
server.)

This does do something. Traffic no longer is routed to the old server
after executing this; however, it is also not routed to the new one...

Does anyone know how to force routers to flush their MAC to IP address
mappings?

Matt