Not a coup.
Operating within the confines of the Constitution - however strained - is allowed. What he so far proposes (openly) is nothing more than the continued expansion of accepted practice. The Legislature writes the bills, the Executive passes them into law and sees they are implemented, and the Judiciary confirms they are allowed by the Constitution - and all members of this system are in place by voluntary vote or appointment as Constitutionally directed.
A coup specifically involves an atypical change of those in power, either contrary to established rules (outright unconstitutional) or within the rules but due to violence or threat thereof (say, President appointing someone to a position vacated due to coordinated death threat).
Obama is NOT staging a "coup" (at least not yet). He seeks election through proper channels (birth certificate aside). No violence has been coordinated or threatened (vague reference to riots by chattering classes notwithstanding). Nobody has vacated their office under unsavory circumstances. While he may seek to introduce un-American policies, he is so far pursuing his goals according to what is Constitutionally allowed. Vigilance is warranted, yes, but don't confuse suspicion with lawbreaking.
I am concerned that many WANT something awful to happen, because that would be entertaining and justify circumstantial fears. Ergo, lots of over-the-top speculation is being generated.
There is indeed reason for concern. Study history, and watch for a repeat of Krystalnacht.
Defend the Constitution - but beware destroying it to save it.