Maybe there is a misunderstanding here about the vocabulary. Even if you append the steady state (zero in your case) to the IRFs as a first point, you will not get a true humped shape pattern… Or I do not understand what you mean by humped IRFs. Usually it is an endogenous mechanism in the model that forces a variable to grow for a number of periods and then decay to the steady state. If you append the steady state in period one (or I would say zero) you will have a jump in period two (I would say one) caused by the impulse. But this is not an endogenous humped shape pattern (which is the effect we are usually looking for) but rather something mechanical (that you would observe even with an first order autoregressive process).
In the IRF plots Dynare draws a red horizontal line (in your case it should be on the abscissa) which represents the steady state. So you already have the information about the steady state or initial condition in these plots.
The IRFs data are stored in oo_ (see the reference manual) so you can do the plots yourself with matlab commands if you want to add the initial condition (steady state) in period zero.
Best,
Stéphane.