There is no HM called Scale. The text says "A Pokemon may be able to scale it" but the actual HM is called Rock Climb.
To get the HM08 Rock Climb, you can find it on your way to Snowpoint City. If you stick to the left side, then you find a house. Go inside and if you see a hiker then you are in the right place. Go behind is house and get the item and it will be the HM.
To get the HM03 Surf, you will find it at the Celestic Town Shrine.