I'm not sure if using anti-freeze to the water would enhance or hinder the electrolysis process.

I Don't believe anybody tried using those blue toilet thingy's to keep the unit clean either

Interesting...so they did use anti-freeze after all.

Now I guess...was the mixture still drinkable afterward, wood be the burning...or not so burning question, as the case may be?

Apparently somebody has yet to try the 'blue brick' technique tho

I've been pondering freezing as well, it is well below freezing where I live and the cell I'm putting together is to be used as a booster in my vehicle   Guess I'll have to play around with different anti-freeze components and post what I find.

Does anyone know of bad/corrosive fumes coming out of these anti-freeze components?

Yep, just do it.  Guess I'm in a good position to test the theory.
Have a nice day.

where I live the water will freeze during the winter. How can I prevent that?

Water in a glass, toilet, bath tub, pond ?

People around here that have fish ponds put in a bubbler. As long as the water is moving it will be harder to freeze.

Looking up the properties of an electrolyte such as Potassium Hydroxide:

http://en.wikipedia.org/wiki/Potassium_hydroxide

We see that it has a saturation point in water of 1.0 grams KOH able to dissolve in only 0.5 grams of water.

The freezing point depression of water can be calculated from the molal freezing point constant for water which is defined as:

Kf = 1.86 ?C  -  kg. water 
                 Moles Solute

So if we make a Table with the calculated values for the freezing point depression of water as Potassium Hydroxide is added we get the following:

%KOH in Water   Freezing Point (?C)   Freezing Point (?F)  
         0                         0.0                      32.0
       10                        -3.7                      25.4
       20                        -8.3                      17.1
       30                       -14.2                       6.4
       40                       -22.1                      -7.8
       50                       -33.1                    -27.7

Once you start getting above 40% KOH in water the viscosity of the solution starts to increase and that is why I stopped at 50% solids.

Theoretically the saturation point of KOH in water is 1.5grams KOH will dissolve in 0.5 grams of water. Calculating that freezing point depression we get a freezing point of:

(1.86?C ? kg water)    (1.0 grams KOH)  ( 1 mole KOH)     =  -66.3?C 
    ( Moles KOH)         (0.0005 kg water)  ( 56.1 g. KOH)

Which is -87?F.  Of course this is theoretical and doesn't take into account solubility changes at lower temperatures. I think the water would be of such high viscosity it would barely move, but it does show how salt based electrolyte can lower the freezing point of water on its own.

I think some type of alcohol would be best.  But your cell can't get hot or the alcohol would boil off and be burnt in the engine.  This wouldn't be an issue for the engine but you would have to replace the alcohol everytime you shut off your vehicle.
Ethanol boils around 172F, 78C and methanol 147F,64C.   Windshield washer fluid is mostly alcohol, HEET is methanol, some fuel stations sell ethanol (don't know the percents.)