You should be able to scroll it using the same technique I used for the followers’ list: first, simulate a click on the inner part of the modal containing the user who liked the picture. Then simulate a press on the space key until you reach the amount of user you’d like to.
By having a quick look at how Instagram is currently, I’d say you could like an article with Selenium by simulating a click on the picture to open the modal. The modal is represented by an
<article/> tag. You could say to Selenium: “Simulate a click on the first button you find in the
This should do the trick.