To get to the attic you're going to need to go into the library (the dark room). There is a book on the wall you can activate that opens the fireplace in the same room. There is a climbable wall in the fireplace.

Once you have access to the attic there's a switch on the wall that opens the basement, then the switch in the basement opens the race track. Go through the race track until you're underground, there is a huge pile of dirt, go up this and open the door. Pack-a-punch is straight ahead.

Here is a video guide if you don't understand the text guide