- post the WMS as an entry in arcgis.com so that AGX can see it (#2 in the Esri support thread posted here)
- post it as a service in the right projection so that AGX can post it (#4 in the Esri support thread posted here)
So here are finally the stacked web services, as we should be able to mashup directly:
ESRI Support also said in #4 above that they're continually improving WMS rendering. Stay tuned for more local services I will add for the Middle East to further create nice web maps!