You can try something like this
var projection = result.AsQueryable().Select(string.Format("new({0},{1})",
model.XtabRow, model.XtabColumn));
var enumerableProjection = (from dynamic p in projection select p).AsEnumerable();
OR
var projection = result.AsQueryable().Select(string.Format("new({0},{1})",
model.XtabRow, model.XtabColumn));
var enumerableProjection = projection.Cast<dynamic>().AsEnumerable();