Problem with MS Loopback Driver

I have implemented a filter at the NDIS layer which redirects outgoing TCP/IP
connections into being incoming connections to a local server (on a differnt port).  It
works fine when online, but in order to function when working offline I have tried installing
the MS Loopback Adaptor.  The filter receives all packets properly and modifies them
just like it does for the real network adaptor, but for the loopback adaptor, my
local server never receives the connection (big problem).  Since I didn't write
the client application, I can't just change the ip address to be 127.0.0.1 or to
be my local IP address (I also can't change the port).  

Summary of problem:
When outgoing packets are redirected to be incoming packets by a filter at the
NDIS layer, it works great for a real network adaptor, but the modified packets
are never received by my server when I use a loopback adaptor.

Questions:
I don't understand how the choice of adaptor can affect the outcome.  I thought that I
modified the outgoing packets to be incoming packets before they ever reached the adaptor,
so how can the adaptor matter??  Is there some property of the adaptor that
causes the higher layers not to accept incoming packets from it?  Is there any
way of modifying settings for this adaptor so that packets that I redirect to appear
to be coming from this adaptor work properly when processed by the higher layers?

Is there anyplace I can download a loopback adapter other than the one from
Microsoft?