On Saturday, March 16, 2013 6:27:31 AM UTC+1, wrote:
Max and XCSoar Team
[...]
Normally these 3 sentences are provided to the LNAV from the GPSNAV/303 combination.

So the L-Nav does not transmit NMEA, it expects to receive them?

We need to do something similar for the LXNAV V7 to get full feature support, the last tiny piece that is missing in XCSoar.

Yes, we could do that. Is there a ticket already? If not, please write one. And be ready to test our binaries. None of us has a L-Nav.
Maybe somebody out there has a spare one and likes to donate it to the XCSoar project? That is usually the best way to guarantee maximum compatibility.