That is incorrect. As soon as you move a force that is equivalent to 4.2 x BW you have exceeded 4.2 x your BW. To lift 520 lbs would require more force than 4.2 x your BW. How much more? It depends on how fast you're moving it (and what planet you're lifting it on but let's assume you've chosen Earth). Squat force calculators estimate the force to be 2834 Newtons which is approximately 637 pounds. So you've overshot and are actually lifting 4.9 x your body weight.
At your body weight you would only need to lift about 403 lbs to create a force equivalent to 4.2 x BW. However, this would not create the correct load because the direction of that force would not necessarily be ideal to achieve your goal (creating bone growth).
Osteogenic loading is based on isometric holding (not lifting) a force equivalent to 4.2 x your BW as measured at the hip. How do you get 4.2 x BW to vertically load into the hip? 1. You can't be bending the hip at the time because that would direct mass in the wrong direction and not simulate bone growth. 2. You can't be moving the weight because that causes more than 4.2 x BW force to be imparted to the hip. 3. Ideally you would stand still and have someone place that 520 lbs on your shoulders. Personally I would suggest finding a resistance machine that does isometric exercises. These are exercises where you push against a plate that doesn't move but the force plate measures how hard you are pushing. (FYI, there is a chain out there providing this type of exercise and physical therapy clinics sometimes have these isometric machines).
For context, I can easily generate a force greater than 8 times my body weight (134 lbs) at the hip but I cannot do a squat with a 45 lb bar. I am leg pressing 200-240 lbs for 8-10 reps after 6 weeks of isometric training. Before starting this training my leg press was limited to 140 lbs.