You need to hit 5 lines on either level in one run. I own both but found it easier on the rooftop level as I was going for my gapes achievement. Follow my video and see where i went for the best results. In a few areas, it is easier to see where the next letter is if you choose the lower lane, and then you can adjust accordingly.
This must be done on endless mode and I do have a fully upgraded character, which may be needed for some gaps/jumps.