Tutorial:
Noclip into a wall. Make sure that you do it first try, or else you'll lose time. Once you're in, you should be in Level 0. If by chance you're in another level, scrap the run (Unless you're in 4 in which case just skip the splits).
Rip up the carpet and kick through the floor of Level 0. You should have trained in prep for this so that you can do it quickly. From here, immediately start running through doors. Entities will aggro, but if you can open doors fast enough you'll teleport before you die. If you end up in Level 0, repeat. Otherwise, immediately start hunting for supplies on Level 4. You want a gun, quite a bit of almond water and something heavy. Make sure you find an exit to Level 6. Enter Level 6, and smash a hole into the ground with your heavy object. Jump in to reach Level 8, and immediately fall on your face to enter level 9. Then, do the Momentum Save to skip the walk to Level 11. From there, triangulate the location of the nearest office building based on Level 11 patterns and Momentum Save into the backrooms of the office. This will warp you to 3999, where you can walk out.