Well, I'm a geologist, consequently used to spend a lot of time in Kalgoorlie. But its just not the sort of place to find microbrewed beers in my memory. Theres Irish pubs (cnr Hannan st and Boulder Rd??) theres old Australian pubs (too many to mention and they change from being hip to not hip by the month, but the Exchange etc on Hannan St, the Palace, the Australian, all good).
So you can get aus beers, and imported UK beers, but its more about the atmosphere than the beer, which is more about how old the pub is, how well done up it is, and what the skimpy barmaids are wearing.
So:
Drive along Hay St (even the family will get a kick out of the brothels with the old stalls).
Go to the lookout over the superpit.
Drive along Hannan St and see which pubs look most happening.
Drive down to Boulder and check out the pubs on the main st there.
If you want to head out of town, have a beer at Ora Banda or at Broadarrow.
Stay out of the Foundry in Kal (could have changed but used to be nasty)
Simon