Setup

Climb on the wall and while scaling it align yourself so that you end up on the right side of the rusted house (green zone on picture), the closer you are to the house the easier the skip is to execute, but also marginally slower. Make sure that before you boost you are aligned upwards. 

During the skip

After you pass the wall perform three boosts in quick succession while crouching, while mid air try to stay on a relatively linear path, you need to get on the highway fast, before you get killed due to being Out of Bounds. Make sure to avoid the highway lights while landing. 

Difference

While on the wall perform 1 boost and immediately after you leave the wall perform a second boost so you don't gain as much height. (Make sure you are not braking right before your first boost or you might end up too high and be killed via being Out of Bounds). Mid air stay on a relatively linear path to get to the highway as fast as possible.