Hi Graeme,
None of the MGL EFIS products contain a WAAS enabled GPS. WAAS is required for ADSB. Therefore you will need the EchoUAT with their SkyFYX GPS.
What transponder do you use? That is important because the ADSB will need to follow and use the same squawk code as the transponder. MGL provides documentation on how to connect one of their iEFIS systems to a Sandia transponder. Here are the links:
http://kb.mglavionics.com/article/AA-01957/0/Setup-of-the-uAvionix-EchoUAT-ADS-B-with-the-iEFIS-and-iEFIS-Lite.html and
http://kb.mglavionics.com/article/AA-01956/0 .
If you don't have a Sandia transponder MGL most likely has a solution for you. However, the Enigma is no longer in production and support for new functionality is less than for the iEFIS & iEFIS lite series. Be patient with their tech support. It sometimes takes a while for them to return emails, but they have always come through for me.
Do you use the data recorded by the Enigma? If not take a look at this program which will allow you to easily see & archive the data:
http://jasflyer.com/-- Michael Jackson
OneX N169XE
AeroVee
MGL Explorer iEFIS
Author of 'Flight Data Viewer'