Removing an auto trans is a bit tedious since you have to detach the torque converter (TC) from the engine flex plate through the starter hole before you drop out the trans assembly with the TC. Do not let the TC fall out when dropping the trans. Once assembly is removed you then slide the TC out of the shaft tube. The seal can then be R&R'd. Good news is you can dump the old fluid out of the TC and refill before reinstalling. This will result in a complete fluid change. I have attached a thread from the resident Guru (JFP) covering the important details.
http://986forum.com/forums/diy-project-guides/41975-removal-torque-converter.html