Zero-inflated Poisson distribution parameter estimates

Let's say we have a population distributed by Zero-inflated Poisson distribution:

$$f(x | \psi, \lambda) = \left\{ \begin{array}{ll} 1-\psi + \psi e^{-\lambda} & \mbox{if } x = 0 \\ \psi \frac {\lambda^x e^{-\lambda x}}{x!} & \mbox{if } x > 0 \end{array} \right.$$

and then a sample with size $$N_s$$ and known parameters $$\psi_s$$ and $$\lambda_s$$.

How can I estimate the confidence intervals for the parameters $$\psi$$ and $$\lambda$$?