The expansion adds another Tallneck to the game. Unlike those form the original game, this one is destroyed.
You can find it in the center of the map. The machine is covered in snow. You will also find Scrappers that detach parts from it. To revel the map, you will have to activate this Tallneck. You need to get the missing parts. Kill three machines to get them. Their locations are marked on the map.
Collect them, go back to the Tallneck and install the parts. You can now activate the machine by using the control panel.
Climb the Tallneck. Use the nearby hills to get on its back.
Sadly, you discover that the damage is even more severe - the protrusions that should allow you to reach the top have been destroyed. Climb on what remained of those protrusions and reach the top.