I'd say have good typography, and use headings with anchor links (href="#foo") with a button next to it, so people can save their position, and return to it later. You can also help with this (for non-touch devices) by using the NYT's emphasis.js: https://github.com/NYTimes/Emphasis.

Manual (not automated) pagination is also an option for letting people know when to breathe.

Otherwise, it's also going to be really hard for people to link to more specific parts of it.