There is no
guarantee that your application will go through under Skilled Migrant - but then, there isn't for anybody. And there is a provision in the rules which sounds as though it applies to your situation, so you may well think it is worth trying.
http://www.immigration.govt.nz/opsmanual/30549.htm
Employment must be ongoing and sustainable. Ongoing and sustainable employment is:
an offer of employment or current employment with a single employer and permanent, or indefinite, or for a stated term of at least twelve months with an option for the employee of further terms, and of which the employer is in a position to meet the terms specified; or
employment on a contract basis where the applicant:
has a consistent history of contract work, and
has a current contract for services, and
INZ is satisfied that such contract work is likely to be sustained.
(my bolding)