Essentially, Bernanke and Paulson plan on paying greater than "market" rates (currently at "firesale" prices because there is no private market) for the securities.
From the article:
The government can help restore liquidity to the banking system by buying depreciated assets at "a price close to the hold-to-maturity price,'' rather than the price they would fetch in the market today, Bernanke said. He also warned the economy will contract "if the credit markets are not functioning.''
Seidman [Note-William Seidman worked extensively on the S&L bailout], who also served as Federal Deposit Insurance Corp. chairman, said a 1990s attempt by Japan to halt that nation's banking crisis failed because the government offered prices that would have drained companies' capital.
The Upshot: Valuation will be for above market rates.