Yes any automotive grease will work. I use the same grease that I use on the u-joints.
No special coupler needed, just stick the end of your grease gun into the fill hole on the swivel ball and count 20 pumps on the left wheel and 20 on the right wheel.
If you turn your wheels "out" the the swivel ball will be easier to put grease in.

 

The grease is for CV-joints also not just the swivel ball seal and I would
feel better if the Oked grease was used for peace of mind.