That reversing circuit WILL work.
If a DPDT switch is layed out like
1 2 3
4 5 6
from the back. This means that 2 & 3 re common. For now, let's assume 3 & 6 are the Normally open contacts and 1 & 4 are thre normally closed ones, thus 1,2 & 3 are related and 4, 5 & 6 are related.
Put a wire between 3 & 4 and connect this to the power supply
Put a wire between 6 & 1 and connect to the power supply.
Take 2 & 5 and connect to the motor.
If you use a DPDT center off switch the motor will have forward, off and reverse positions.
Unless your motor has a diode across it's terminals, it will work. I will assume that you have already connected the power supply in reverse to the motor tuerminals and it reverses.
Dishes work the same way. They have two hard limits as described earlier built in. Adustible limits are rare.
Position for dishes are usually by two methods:
1. Hall effect (counts pulses); an open collector transistor and a magnet, +5V power is required
2. Optical Same deal; open collector, +5 volt power is required.
3. A micro switch that creates a pulse.
There is an INDEX position that the controller can use to find itself. A typical motion controller will reverse until it hits a hard stop and check along the way whether or not INDEX was found. It will then go in the forward direction SLOWLY until the INDEX position is found. This is standard protocol.
A 4th method which is not seen on satelite dishes is the potentiometer. Basically a resistance is proportional to position.
Now if your motor is something wierd then you may have to do strange things, The DC motor we are assuming here is a permanent magnet DC motor.
You must be able to answer this question as true:
Does the motor reverse when the polarity of the power supply is reversed on the motor?
Second:
Do you own a multimeter?