Нашел ответ:
if (!MapResourceManager1.Initialized)
MapResourceManager1.Initialize();
ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer.MapResourceLocal mrl = (ESRI.ArcGIS.ADF.Web.DataSources.ArcGISServer.MapResourceLocal)
MapResourceManager1.GetResource(0);
IMapServer ms = (IMapServer)mrl.ServerContextInfo.ServerContext.ServerObject;
IMapServerObjects2 mso = (IMapServerObjects2)ms;
IMap map = mso.get_Map(ms.DefaultMapName);
IFeatureLayer2 layer = (IFeatureLayer2)map.get_Layer(2);
IEnvelope envelope = new EnvelopeClass();
ISpatialFilter spatialFilter = new SpatialFilterClass();
spatialFilter.SpatialRel = esriSpatialRelEnum.esriSpatialRelIntersects;
IFeatureCursor fcursor = layer.Search(spatialFilter, true);
IFeature ipfeat;
string s = Map1.MapResourceManagerInstance.ResourceItems[0].LayerDefinitions["2"].Name;
TreeView1.Nodes.Add(new TreeNode(s));
for (int i = 0; i < fcursor.Fields.FieldCount; i++)
{
ipfeat = fcursor.NextFeature();
TreeView1.Nodes[0].ChildNodes.Add(new TreeNode(ipfeat.get_Value(2).ToString(), ipfeat.get_Value(0).ToString()));
}