How many O'douls non alcoholic beer can you drink and still be okay to pass an ignition interlock test?

Depends solely on a number of factors. O'Douls beer has 0.5% ABV, and II tests require you to have a BAC < 0.02. Since BAC varies per person because of weight and body build, I cannot give you a definitive answer. Drinking and driving, regardless of whether you are over the limit or not, is considered illegal, and yes, you can still get arrested for driving under the influence of alcohol, even if you have only had 1 beer.