Added example/test for http://stackoverflow.com/q/16796519/23354

Tests/Tests.cs

@@ -12,6 +12,7 @@ using System.Reflection;
 using System.Dynamic;
 using System.ComponentModel;
 using Microsoft.CSharp.RuntimeBinder;
+using System.Data.Common;
 #if POSTGRESQL
 using Npgsql;
 #endif
@@ -1613,6 +1614,36 @@ Order by p.Id";
             connection.Execute("drop table #Users drop table #Posts drop table #Comments");
         }
 
+        public class DbParams : Dapper.SqlMapper.IDynamicParameters, IEnumerable<IDbDataParameter>
+        {
+            private readonly List<IDbDataParameter> parameters = new List<IDbDataParameter>();
+            public IEnumerator<IDbDataParameter> GetEnumerator() { return parameters.GetEnumerator(); }
+            IEnumerator IEnumerable.GetEnumerator() { return GetEnumerator(); }
+            public void Add(IDbDataParameter value)
+            {
+                parameters.Add(value);
+            }
+            void Dapper.SqlMapper.IDynamicParameters.AddParameters(IDbCommand command,
+                Dapper.SqlMapper.Identity identity)
+            {
+                foreach (IDbDataParameter parameter in parameters)
+                    command.Parameters.Add(parameter);
+            }
+        }
+        public void TestCustomParameters()
+        {
+            var args = new DbParams {
+                new SqlParameter("foo", 123),
+                new SqlParameter("bar", "abc")
+            };
+            var result = connection.Query("select Foo=@foo, Bar=@bar", args).Single();
+            int foo = result.Foo;
+            string bar = result.Bar;
+            foo.IsEqualTo(123);
+            bar.IsEqualTo("abc");
+        }
+
+
         public void TestReadDynamicWithGridReader()
         {
             var createSql = @"