This works best if you have initially registered either a single Action or if you have given your action an Id. I'll show both ways:
Using ts AsNew TaskService("YourRemoteServerName") Dim task = ts.RootFolder.Tasks("YourTaskName") If task IsNotNothingDim action = task.TaskDefinition.Actions["YourID"]; ' Dim action = task.TaskDefinition.Actions[0]; action.Arguments = "new argument string" task.RegisterChanges() EndIfEndUsing