Add "Allow in the background" items from command line

Some of the applications on my system run only if they are allowed to run in the background. I want to run these apps only in certain time windows. Due to this, I am manually enabling the app in System Settings -> Login items -> Allow in the background and then once I am done with using the app, I am disabling it. I want to write a cron job to automatically enable/disable items in the background. Is there a way to do that from command line or osascript?