What is the test for evidence of aiding and abetting liability in a murder case?

Section 22, subdivision (b) provides that "[e]vidence of voluntary intoxication is admissible solely on the issue of whether or not the defendant actually formed a required specific intent, or, when charged with murder, whether the defendant premeditated, deliberated, or harbored express malice aforethought." "[T]he intent requirement for aiding and abetting liability is a 'required specific intent' for which evidence of voluntary intoxication is admissible under section 22." (People v. Mendoza (1998) 18 Cal.4th 1114, 1131-1132; see also People v. Curry (2007) 158 Cal.App.4th 766, 786.)