I refer to this article.
I also use ASP.NET and I got the following button click event:
protected void Button1_Click(object sender, CommandEventArgs e)
//Do some stuff
You can absolutely call it still, it is just a normal C# method. But the caveat is that you need to provide correct values as command name and command argument, as this handler most likely uses one or both of these.
string commandName = "command name here"; object commandArgument = <argument here>; Button1_Click(sender, new CommandEventArgs(commandName, commandArgument));
That is assuming you call it inside Page_Load, as the post you refer to. If not, make sure to provide reference to correct control as