My TJ didn't have any interior lights when I bought it but the connections were there - the 'footwell lights' or 'courtesy lights' are mounted under the dash - there are 2 short pigtail connections running off the wiring loom along the bottom of the dash.
You can tap into these for some LED strips like Cornelius or get the standard fittings and plug them in.
The globes in the standard fittings run VERY HOT so I'd recommend replacing the standard globes with LEDs anyway.
I got my standard 'courtesty lights' fittings here...
http://www.jeepsareus.com/p/MB72-1.html
They weren't a direct plug in on my 97 but should fit all later years no probs.
As for the 'Dome light' - My TJ didn't have a sound bar or a dome light when I bought it - so I got an aftermarket sound bar with a light in it - I drew power straight from the battery (with a switch and fuse).
The dome light doesn't come on when I open the door but that's OK with me.
Then, one thing led to another....
Ended up putting green LEDs everywhere (including air vents LOL)