Right now you can't. The changes to the expungement law that made felonies eligible do not apply retroactively. Also, Governor Walker refuses not only to consider granting any pardons, but even to staff the board that considers pardon applications.
Even if you could persuade a prosecutor and a judge to issue an expungement prohibited by law, it would not eliminate the police record of the arrest and conviction which employers will see upon conducing a police records check on you. Felony convictions don't just disappear in Wisconsin.