There is no mechanism to do that..........
Legally? No. Obamaly? Exec orders, a military filled with his people in/atop the Joint Chiefs/CIA/FBI/NSA and the MSM telling the people its OK is one that will work though.
Not for long...but it will work long enough for hell to start.
There is no mechanism to legalize millions of illegal aliens either. If DOJ says we want to investigate they will.