First of all your question is not that clear.. still i would like to help with what i understand from your query.
Sec 24(b) would allow deduction of interest paid only when the structure becomes a Residential House Property and not before that. You can claim deduction under Sec 24 only when you have something taxable from the HP in question.
1) The comletion has taken place in PY 2010-11.-----------So there will be no implication of any income or deduction in the P.Y 2009-10 for which you would b filing the return
2) The house is not yet possessed.----- This point is not that relevant to this case
3) Registry is Pending.--------- In IT Act, registered ownership of property is not to be seen at most places it is the beneficial ownership that should be seen.