This is more easily done if you have an aftermarket cooler where you can detach the return line. Remove the line from the cooler and put a plug in it. Run a length of tubing from the open port on the cooler into a clear container precisely marked at 2 quarts. Run the engine until the fluid pumped into the container reaches the mark, shut it off. Add two quarts, repeat 7 times. The trans system holds a bit over 13 quarts, so the routine I'm describing will replace virtually all the existing fluid.
The reason you have to stop at two quarts, the trans pump will quit moving fluid at just a bit more that that.
Jeeps: Where my 401(k) went to die!