Well, there's this: http://www.freedeskt...ager/Debugging/. Of course, instead of the systemd commands, replace with /etc/init.d/NetworkManager stop, etc.
Is it a service? It has an entry in /etc/init.d? Then it's easy, you can put it in rc-update, which is really just a wrapper for putting links in /etc/runlevels.
You could create a service file in /etc/init.d , it wouldn't be too difficult, just use existing files as a guide.
If not, then you can put it in your /etc/local.d/*.start file. Create one if you don't have one already, there is an explanation file in that directory. Something like this would work:
Or if there is a timing error with the startup of NetworkManager that way you can always do it with a startup file, say in your home directory. It'll have to be owned by root and you'll have to add it to /etc/sudoers by way of sudo visudo, an entry like
<username> ALL = NOPASSWD: /home/<username>/<filename>
. This file would be like:
Then start that file with sudo <filename> in your desktop startup stuff or .xinitrc if you use that.
Listed in order of preference. I don't have ModemManager, so I can only suggest general ways of handling it.