Yep. In a heartbeat. Temporarily probably, since I'm not experienced in many areas where a President should be experienced; nor am I in good enough health physically; so I would try to pave the way for someone who does have those skills and who is in better health. But I'd do better than Obama because he has a wrong agenda in 90% of the areas of his responsibility.
Policies-----I would fire most of the Cabinet and most of the appointees and replace them with people who actually care about the morality and integrity and strength of our Nation. Fire Joe Biden if it were possible. If not, recommend impeaching him. Then I'd compose a speech expounding for all Americans how to interpret the Constitution in the proper way instead of the twisted way Obama has portrayed it. That would be a step in correcting most of the errors of the current Administration!
Go around the political roadblocks? Those ARE the main political roadblocks.
But I think you're asking specifically how to do things within the scope of current legalities. Hmm....it might take some time. But the thing that comes to mind is to surround myself with people who will help come up with ideas about how to legally do that. After all, a President doesn't exist in a vacuum nor should he act totally on his own........wise advisers and well-experienced people are critical to an Administration. I wouldn't have to be a tyrant in order to get rid the consequences of the actions of the current tyrant. America is a Republic first; that would be upheld via adherence to the Constitution; then I would re-institute democracy based on those principles.