Read through these instructions before beginning. Many skateboarding shops have special tools for taking out skateboard bearings, and they usually provide this service for free. However, removing your own skateboard bearings is simple. Just be careful - while taking the bearings out of the skateboard wheels is easy, it's also easy to accidentally damage your wheels if you aren't careful.
As for special tools, all you need are the tools to remove your wheels - any skate tool or set of screw drivers and wrenches will do.