RtmAddNextHop() Example Code

I'm writing some code to add a route that uses RtmAddNextHop(). Does anyone
have some example code to help me fill in the RTM_NEXTHOP_INFO structure,
specifically the InterfaceIndex field? The example in the SDK wasn't very
helpful.

Ideally, I want to get a list of the interfaces currently on the system and
chose the
interface associated with my PPP connection, which changes each time the
interface
is connected.

Thanks,

Jerry