Unfortunately I found some time ago shorting stocks is limited and unreliable on the ASX using IB.
I don't know if this has changed for the better or worse but I only short on the US exchanges (14,000 + stocks to choose from and greater liquidity) but this I guess wont suit most here at ASF.
I also around the same time stopped trading short on the ASX due to the rip off commissions charged by Oz brokers or CFD providers, limited order types and often the drop in liquidity on some stocks.
IMHO these issues add up to become a sizable risk to my account easily mitigated to some extent by trading short in the US.
Hope this helps