Boy, I was just making a tutorial... I quite close to starting that part. You need to place the path_track entity right above the place the train should be while the trackchange is working. Place a second path_track in the same z cordinates(top view). If you want the lift to move upward place it above original path, if you want it to move downward then place it below, or you can place it in the same place like in powerup.
The train to switch value determines which tracktrain will be affected, The top and bottom track part is quite self explaintory.
The spin amount is how much the lift will spin(in degrees)- 45, 60, 90, 135, 180, 360...
And the travel attitude is how high in unit will the lift move.
I asume you need to make the path_track that is right above that trackchange/autochange target the trackchange. Usally you would use the 'fire on pass' value to trigger stuff with path_tracks but since this is technicly a dead end(the first and second track ends there) you should use the 'fire on dead end' value to activate the trackchange.
One last thing- the sole diffrence between the trackchange and autochange entities is that the autochange affects non player controled trains while the trackchange affects player controled ones.