It's difficult to press the joystick downward to expose the groove, push the actuator up, and try to press the e-ring into place all by myself. 
Yup.
And it's easy to ding up the actuator in the process. Fortunately, Happ sells replacements for a few cents each. I ordered some of those as well as a few extra clips.
And yes, needle-nose pliers are the way to go to get it on. To get it off, use a slotted screwdriver -- be sure not to pry it ALL the way off with the screwdriver, though, or it will end up somewhere on the other side of the room. (See "spare parts," above.)

-- Chris