Little known twistd feature:
exarkun@boson:~$ cat foo.tac
from twisted.application.service import Application, IProcess
application = Application("Demonstrate twistd process name support")
IProcess(application).processName = "name-demo"
exarkun@boson:~$ twistd -y foo.tac
exarkun@boson:~$ pidof name-demo
11097
exarkun@boson:~$