About the only way to replace them is to pull the block and pull them out, there just isn't enough room to get in there and safely not kill yourself otherwise. You need clearance of about six inches minimum to get in there and mess with it, more room is better.
It is much easier to pull the motor out to do it. I had to replace a freeze plug on my Lebaron and is was the one right behind the starter and Turbo. I really don't think I could have done it if the motor was still in the car.
I managed to get one out on my 89 Sundance that had been leaking a long time! It wasn't bad coming out, but had to put a rubber expandable one in until things warm up and i can pull the motor to do it right.