Schwinger-Dyson equation help

in Pages 307-308 of Peskin and Schröeder we find

$$\delta S (< \Omega | T( \phi (x1) \phi(x2)..... \phi (xN) | \Omega >)= -\sum_{n=1}^{N}< \Omega | T( \phi (x1) \phi(x2)..i\delta (x-xi)... \phi (xN) | \Omega >$$

they are the Schwinger Dyson equation for the correlation function , my question is , how could i use Wick's theorem to compute the quantity

$$< \Omega | T( \phi (x1) \phi(x2)..i\delta (x-xi)... \phi (xN) | \Omega >$$ for every 'i'

here $$\delta S$$ is the functional derivative of the action 'S'

Avodyne