The cable, I think, is standard. The end at the hub is a adjusting long barrel that screws onto the indicator. You can also get an adapter that is basically the adjusting barrel with a cable clamp so you can use a different cable.
Equally important, and perhaps more difficult: do you have the correct indicator for the hub? The indicator for the four-speed hub can be hard to find.
I can't find a photo of the four speed indicator, but the three speed one, which is common, looks like this:
Do you have something that looks more or less like that?