If you have access to air tools and a decent compressor it will make your life alot easier, that's what air tools are made for. I have never had to bench press a transmission out of a car but aparently it can be done. With the correct tools and a hoist it takes me about an hour or less to replace that seal. You might want to scrutinize the other seals that are accesible only when you have the trans out, like the input shaft seal and the front pump seals. If the car has over a 100K on it, what red engine doesn't anymore, I always recommend them.

Mark