Replacing a cutlass bearing is not a tough project but does require some thought. On some boats the bearing is inside the dead wood making replacement more of a task than when it's mounted in a strut. These instructions deal with replacing a strut mounted cutlass bearing.
While there are some commercial tools designed for cutlass bearing removal they a bit pricey for a DIY to replace just one bearing. Some owners associations have purchased them and allow their members free use of the tool. The Catalina 34 organization owns one such tool. They work well however and don't require the shaft be removed, a big plus.
Occasionally when a bearing has been installed for a while they can become frozen or corroded in place. In these instances the shaft would need to be removed anyway even if you had a cutlass bearing tool. This article focuses on the removal of a cutlass bearing once the shaft has already been removed.