I thought you'd ask me that question...lol! I did pull the ABS sensors, temporarily, of course.
Using the grease gun, I put a slightly larger zerk fitting at the end of the grease gun. I didn't screw it in to the hub, but I held it against the ABS opening and pumped away. After awhile it starts oozing out of the hole. I then try to push the grease back in, or as much as it will take. Then I re-install the ABS sensor plug (sans the wire, of course)...and that's about it.
This was before I learned about the Riff Raff Diesel fittings.