The only special tool needed is a dial gauge to properly set the axial play in the wheel bearing, but there are backyard methods of setting this play without special tools.
Yes, there are special techniques and steps that must be followed when replacing or regreasing a wheel bearing. This has been discussed in detail in the past. Try searching archives using keywords such as "wheel bearing", "axial play". Arm yourself with information before undertaking this job, because anything less than doing it properly will result in premature failure of the bearing.
Here is a link where I had my say:
link