If you are just changing the hub, you shouldn't be messing with the bearings.
If you are replacing them because you can, then from the pictures, it doesn't appear to be a special snap ring. You may just need a larger pair of pliers.
And as mentioned above, use care when reassembling the hub. You must support the inner bearing race when presssing the hub back in.
I was going to replace the bearings since I was already in there. However, the hub is super tight and only got it to move a 1/4". Guessing 150lbs on my compresssor isnt enough.
Anyways...on the diagram the clip looks like its 2 closed loop ends but on mine its not. They are open and angled. I have a bunch of different tips for the clip pliers but I guess the pliers are to small for this ring clip like you mentioned.
If there are no holes for you to grab the ring with, then just pry the thing out. Use a couple of small screwdrivers and get behind it and lift it out.
If the hub is in there that tight, you may need to take it to an automotive machine shop or somewhere they have a press.
If you do it wrong, you can damage the knuckle or the bearings or the hub.