win32 adding a tcpip alias to an interface

[David Bear]

I've never used the win32 extensions to python.  Most of my python
tinkering has been around unix.  However, I am contemplating a script
that would add a second ip address to an interface.  Here's the
general idea:
1) when a windows box starts, it gets a dhcp lease on a non-routable
IP address, web browsing is handled through NAT
2) if the users needs a fully routable ip address, he authenticates to
something -- this could be Active Directory, Samba, Kerberos --
something else.
3) after successful authentication the user is given a fully routable
ip address 

So, the python script would need to handle 2 and 3.  There are
probably classes someone has written to do authentication (haven't
looked yet)  But, I'm worried about how one might add an ip address to
a windows tcpip stack.  Anyone have any ideas how to do this?

tia