tcpip.sys interface

Hi!

I am writing NDIS protocol driver for Vista, which is to send and receive some multicast packets.

Is it possible to make TCP/IP stack driver (tcpip.sys) encapsulate my messages within IP packets?
How can I communicate with it?

I tried to find IOCTL-s which would help in communicating with tcpip but there are no such for public use.
Winsock Kernel is not an option as well, as it provides functions for the transport layer :/ whereas my driver (multicast) works in the network layer.
There is also TDI but it only allows for manipulating with routing and ARP tables.
It does not provide interface to send simply ipv4 packets which is of my interest mostly.

Any help will be appreciated. Thank you!