You can set
SelectedIndex
property for the combobox after doing data binding.
Update: This just works.
List<MyClass> lst = new List<MyClass>();
lst.Add(new MyClass { MyProperty = 1, MyProperty1 = "1" });
lst.Add(new MyClass { MyProperty = 2, MyProperty1 = "2" });
lst.Add(new MyClass { MyProperty = 3, MyProperty1 = "3" });
comboBox1.DataSource = lst;
comboBox1.DisplayMember = "MyProperty1";
comboBox1.ValueMember = "MyProperty";
comboBox1.SelectedValue = 2;