A SERMON on the way to jail: “Even before the ink dries on his guilty plea, William S. Lerach is trying to rehabilitate his shattered image as the heroic defender of little guys suffering at the hands of nefarious corporate titans. . . . out of more than 1,500 words lambasting greedy Fortune 500 executives, Lerach devoted only four sentences to his Sept. 18 admission in federal court to having conspired, according to his plea deal, ‘beginning on or before 1981 and continuing through at least 2002 … to obstruct justice by corruptly influencing, obstructing and impeding, and endeavoring to influence, obstruct and impede the due administration of justice in lawsuits filed and litigated in the courts of the United States.'”