If you want to do it using wsadmin scripting, I think this should work. No promises though, I haven't tested it.
node_name = 'TestNode'
server_namess = [AdminConfig.showAttribute(id, 'name') for id in AdminConfig.list('Server', AdminConfig.getid('/Node:%s/' % node_name)).split('\n')]
for server_name in server_names:
AdminControl.stopServer(server_name, node_name)