ソースコード

using System.Reflection;
using UnityEditor;

public static class Example
{
    [MenuItem( "Tools/Hoge" )]
    private static void Hoge()
    {
        var assembly      = typeof( Editor ).Assembly;
        var type          = assembly.GetType( "UnityEditor.ConsoleWindow" );
        var consoleWindow = EditorWindow.GetWindow( type );
        var methodInfo    = type.GetMethod( "SetFilter", BindingFlags.Instance | BindingFlags.NonPublic );

        methodInfo.Invoke( consoleWindow, new object[] { "ピカチュウ" } );
    }
}

参考サイト様