I am facing this issue, having just started looking at this web part.
If someone solved this, please share some guidance.
First I will try seeing what this "Location on Map" custom column does. I assume there so brief logic that looks for the specified lat/long (or addr) columns, and does some computation.
Ninja here suggested (I believe) that it could be solved by building a SL xap extension to the web part. Can anyone share what methods would be overridden and/or implemented for this? I am imagining there would be 1) an onDataLoad method you implement that takes the SPList data lat/long, and performs the calcs that otherwise the Location On Map ArcGIS column would perform, and 2) ??? maybe no 2.
Another thought was seeing what I could do in SP Designer to this External List, perhaps simulate the Location On Map using the designer. Haven't tried yet.
Looking for ideas. If xap extension is the only way, can someone give me clues on methods and/or links to real life examples. The ArcGIS MessageBox example leaves a lot to be desired.
thanks!