At between 2% - 10% per months subject to the LVR it would be doable.
Usually max 80% inclusive of rolled up interest on residential deal.
Preference of course for 70-75%.
Chris have to say why second mortgage.
Would be doable (subject to lvr etc etc) but certainly isnt going to be cheap especially under lodoc.
To be honest depending on the amount required probably be cheaper to refi and increase the loan accordingly.