Yeah, the government will have access and control to the "toxic assets" from the corporations. But it also includes sweetners as I mentioned earlier.
He injected $4bn into the non-bank mortgage sector by purchasing AAA mortgages, thus giving a such for the smaller instutions to gain an advantage in competition (due to lower interest rates for them, govt is the owner --> paid 4bn, injected into the economy), thus becoming much more competitive in the mortgage market.
Btw, costa, generally to "put" money into the economy is from Open Market Operations (OMO). If the RBA purchases a large number of second hand securities, this will inject money into the economy as the bank is paying for the securities in the open free market. However, if the RBA sells second hand securities then this reduce the amount of cash avaliable in the economy as the free market has bought the securities for cash.