SAN FRANCISCO — The latest firm to step into shareholder litigation over Hewlett-Packard Co.’s disastrous acquisition of British software firm Autonomy Inc. is Skadden, Arps, Slate, Meagher & Flom.

Palo Alto partners Allen Ruby and Timothy Miller formally entered appearances Monday as counsel to a dozen members of HP’s board of directors, including Netscape co-founder Marc Andreessen; Booz & Co. CEO Shumeet Banerji; and McKesson Corp. CEO John Hammergren.