At last!!! I found the way to use the ImpEntity!!!
If you use AutoCAD MAP 2008 and .NET 2.0 then you have to use this file to get the examples:
sdk.dev.net.gis could be the chm or the pdf, that is located inside the AutoCad folder and Help folder...
There I got the info, the best example is:
AcMapMap currentMap = AcMapMap.GetCurrentMap();
MgFeatureService fs =
AcMapServiceFactory.GetService(MgServiceType.FeatureService)
as MgFeatureService;
MgLayerCollection layers = currentMap.GetLayers();
MgLayerBase parcelsLayer = layers.GetItem("Parcels");
string fcName = parcelsLayer.GetFeatureClassName();
MgSelectionBase selection = currentMap.GetFeatureSelection();
string selectionFilter = selection.GenerateFilter(parcelsLayer,
fcName );
MgFeatureQueryOptions queryOpts = new MgFeatureQueryOptions();
queryOpts.SetFilter(selectionFilter);
MgFeatureReader featureReader;
MgResourceIdentifier fsId = new
MgResourceIdentifier(parcelsLayer.GetFeatureSourceId());
featureReader = fs.SelectFeatures(fsId, fcName, queryOpts);
With that you get the selected feature, and with a featureReader.ReadNext(); and a featureReader.GetString(#); you get the value from the property # (number of the property), you can explore the MgFeatureReader class to get more info...
