In principle, yes, I could definitely support something like this. A huge portion of auto fatalities are alcohol-related. If the technology is effective enough to prevent the person from driving while intoxicated, without lots of "false alarms" for sober people, then I absolutely support it. It could save tens of thousands of lives per year.
I think people dramatically underestimate how dangerous an automobile is. For most of us, it's by far the most dangerous thing we own.