Temporary int'l consulting contract, if arrival delayed?

I'm supposed to arrive in the State on December 1st, on a Green Card, to begin employment with a company that I'm already working for through an outstourcing company. Unfortunately, I may have to postpone my arrival to January.

Would it be legal for my Irish employer to take me on for a month (in December) as an international contractor/consultant, even though we have en employment contract?

yeah no problem, so long as during dec you are working for them from outside ireland. if your employer is big enough, they know this rule and wont cause any damage.. if micky mouse one (lots of them in ireland - you will be shocked when you come here and join!) then be very careful.. such stuff cause severe damage and you are responsible to know the laws