You mentioned you are using isboxer. I would setup a video fx region on your slaves that broadcasts the action bar area with the buttons/spells you want to monitor. Then set up a source on your paladin.

You can also try Jamba. But I had an issue with Jamba not correctly tracking a Paladin cooldown, so I'm not entirely sure Jamba is tracking all the other cooldowns correctly. Basically, jamba will display a countdown bar on your main whenever a proc happens on your slave, it doesn't show cooldowns though like the method I described above with the action bars and isboxer.

Good luck.