Will a breath alcohol ignition interlock device work with msd igntion system?

Yes, an interlock device will still work. An MSD box is an after market brain that fires the spark plugs in performance vehicles and has nothing to do with engaging the starter motor. The interlock device is installed between the ignition switch (key) and the starter motor relay or solenoid and is independent of the secondary ignition system. (Where the MSD box is located)