Use your fingers to get the rings in. Take your time as it can be frustrating if your impatient. You can do it yourself, just keep it cool.
Even though that guide is a different length, it should be fine. I did it on mine without issue.
Make sure all surfaces are clean, flat & dry. I think using copper coat is a good idea, but its up to you.
Make sure you dont leave anything out during assembly steps, like o-rings, dowls, or it'll have to come back off.
Here is a video on some basic instructions. Take what you will from it.
https://www.youtube.com/watch?v=9ll19_DSkTM