Not terribly difficult. You'll need a ratchet and socket set, jack stand, and a floor jack with wheels.
First, support the rear of the transfer case with the jack stand. Next, support the transmission skid plate with the floor jack and remove the 6 mounting bolts. Also remove the 2 transmission mount bolts in the center of the skid plate and the stabilizer bolt nut.
Lower the skid plate and move it out of the way.
Remove both front and rear drive shafts. Now the speedometer cable, vent & vacuum lines. You will also need the remove the range lever linkage on top.
Place the floor jack directly under the transfer case and lift it enough to take the weight off the jack stand. Now move the jack stand and place it under the transmission.
Now you can remove the transmission to transfer case bolts.
Once the bolts are out, pull the transfer case and jack together directly backward to separate it from the transmission.
If possible, have a friend help stabilize the transfer case. Don't let it fall off the jack.