Hey it all depends on your wifi shield, but remember just connecting the ISCP pins will not work, there could be up to 4 more pins that you'll need to try, on the uno the wifi shield uses the ISCP, pin 10, pin 4, Tx and Rx to work properly
ISCP, Tx and Rx are for the main comunication(remember all depends on your wifi shield)
pin 10 is used for slave select (THIS IS VERY IMPORTANT) for the wifi shield
pin 4 is used for slave select(Slightly less important) for the sd card(if installed)
ISCP pins are actuall the SPI interface pins aswell, so you have mosi (Master out slave in)
miso(Master in slave out), SCLK (Serial clock), Reset, and your power (Vcc and Gnd)
But in SPI if you ever used it you can have multiple devices connected to one serial line, but if all were sending data it would look messed up, so you have slave select to select which device can talk at once. So if you want to send a packet to the computer you would need to bring pin 10 (Wifi) to Low and 4 (Sd card) to high), remember slave select is weird, HIGH = Off, LOW = ON. just remember that.
So if you wanted to make the esplora wireless i would suggest this connect pin 10 and 4 on the Wifi shield and connect them to some unused pins on your esplora, then either go into the wifi library and change those pins to the ones you have selected on the esplora or if you can't find them, do it manually by doing pinMode, digitalwrite(pin, HIGH) for off or pin, LOW for on