Can a slider be used on -

Leadcore set up
Dipsy/Divers set up

as well as downriggers or should they be used on downriggers only ?????

Sliders are used on downriggers, as they slide up and down the vertical'ish line from the rod tip to the ball release, you can use a fixed slider in a dipsy but it would be a major hassle trying to do it our lochs are just too small for it to work successfully.
To do it you put out the dipsy then rig up a slider with an Offshore line clip on it put out the dipsy 50ish feet then clip the slider on and hold it inplace with the offshore clip that has the slider line threaded through one of the holes at the back of the clip, this will hold you spoon 50 ft away from the dipsy, them let the dipsy out another 50ft or so, you end up with the dispy 100ft away and a spoon midway on the line 50ft away, if it goes wrong you will have the mother of all tangles, and if you get a decent sized fish on it you will need at least 3 in the boat, one to steer, one to play the fish and someone else to sort out any tangles that might happen on the way in.

I dont fancy trying it

cheers...james

Cheers for that info. I think I will stick to the slider on the Downrigger

Nope i would rather tightrope walk along a barbwire fence naked

That could bring a tear to a glass eye