Are you sure it's transmission fluid and not oil from the rear main seal that has blown back from the bell housing?
To directly answer your question, put a jack stand or jack of some kind under the bell housing of the transmission before you loosen the skid plate to prevent the driveline from dropping. I used a rolling floor jack under skid plate, that helped to keep it snugged up in place as I removed all six bolts then slowly lowered it and rolled it right out from under the Jeep. Remember the transmission mount is also bolted to the skid plate by four bolts.