You may try to do it with a piece of pipe as Shaun suggests (I have done it successfully in one case) but, unless it was replaced thoughtfully by the manufacturer or last boatyard (which is rare in my experience), you will need to remove the shaft along the lines of the process Maine Sail describes. I agree that my fellow Mainer is a bit over the top in his OCD and his way or the highway, but his site does have the best pictures and lots of good suggestions. He has done the work and that entitles him to a bigger voice than folks who did it once on their boat. By the way: despite the fact that everyone is calling it a "Cutlass" bearing, the name is actually
"cutless" from the brand name of the original replaceable bearing manufacturer. Look it up.