I am sorry my colleague also seems to be unaware of Joseph Nagar, but what he says is to ask for "Vallalar School Stop," a prominent landmark in Sathuvacheri, and get down and make an enquiry there. Alternatively, and probably the best way he says, is to alight at the Vellore bus stand and to take an auto, hardly 2+ km. For this, he says to board only buses that go inside Vellore town and not the ones that take the bypass.