Routing packets through specific interface

[Alex]

Hi,

I have a host with an ethernet interface and an alias that I've
created. I need packets to specifically be routed through the alias
interface because that is the IP address the remote host is expecting.

Should I do this using SNAT or otherwise with iptables? Does someone
have an example they can forward on for routing all packets through a
specific interface?

Just to be clear, when I telnet to a specific port on a remote host,
the remote host receives it as the primary interface. It should be
leaving the source through the virtual IP.

Thanks,
Alex