The method ClearLog() for clearing VoiceAttack's event log was introduced in v1.7.0.2. You can use the functionality in a VoiceAttack command by simply adding an inline function to your command and inserting the following (this is for C#):
public class VAInline
{
public void main()
{
VA.ClearLog();
}
}
You don't need to have any reference assemblies.
Cheers!