It takes a little time... Get some good high temp rated bearing grease that is rated for disc brakes and smear a good bit of the grease in the palm of your hand.
This presumes that the old bearing has been cleaned and do not rotate the bearings dry with compressed air!
So anyway, dab a golf ball sized gob in the cup of your palm, spread it out so that you have a mound about 1/2" high...
Take the new bearing in your other hand and slap the edge of the bearing into the gob repeatedly until the new grease works it's way to the top and then start to rotate the bearing very slowly as you continue to "pack" the bearing.
It does take awhile but this works better than that thingamob that you stick a grease gun on the top of...
It took me about ten minutes to repack each of my bearings on the D60 and there are 4 of them...
If you are worried about chemicals, wear latex gloves...
►►►►If you have automatic lockouts, DON'T FORGET TO USE A PICK TO PULL THE RETAINING LOCK CLIP OUT!!!◄◄◄◄
If you break the clip, you will have to decide to either convert to manual lockouts ($250) or spend $44 for a new clip...
Don't ask me how I know...
If you decide to go with a new clip, then you are faced with having to wait for it to be delivered. If you don't have the patience, then that little clip will cost you $72 with the two day shipping charges included... Quad 4x4 really gouges us with this clip, but as far as I know,
they are the only ones who have them.