Running xautolock upon login to X

[Robert Mosher <mosher@andrews.edu>]

I am looking for a way to automatically run xautolock (or any other
program) when I first start an X session, regardless of how I enter X
(startx, XDM, GDM...) or what window manager I'm using. I've tried using
the .xinitrc and .xsession files, but with no success.  How should I go
about this? 

Thanks,
Rob Mosher