I saw a bearing repacking tool similar to this (the other was metal) on one of those 4X4 shows on tv recently. It looked like it would fill the rollers evenly, and be a lot easier than doing it by hand.
The roller bearing goes between the two plates. The main bolt is hollow (closed on the ends), and although you can't see it in the picture, also has a second hole in the bolt in the area between the two plates where the bearing will be. Once the bearing is placed on the bolt and centered between the two plates, a grease cerk is inserted into the other hole in the bolt, and a grease gun can then be attatched to send grease through the bolt and out through the bearing. Easy squeezy.
I use this, it works great. Also, the manual states repacking every 15k if I'm not mistaken. It's not a bad job at all.. just dirty. RAGS RAGS RAGS... I got a paint can of part washer, it came with a basket, works great.