There isn't a way to have sql server listen on a specific ip. Sorry.

If you haven't already seen this, take a look at the Network
Configuration dialog on the general tab of the server's properties.
Two protocols are enabled by default. TCPIP is one of them, and you
can change the port and set it to ignore discovery broadcasts. That
would make the server invisible to anyone looking for it. However,
anyone who portscans the server would notice whatever port you put it
on and (I'd assume) be able to figure out that it's a SQL Server. So,
you do still need to firewall it.

The other protocol is called Named Pipes. That's basically using
memory to communicate. If the application you're developing supports
it, I'd suggest using this and turning off TCPIP support altogether.
This is probably faster anyway.

Chris