I've been messing around in zero editor, and I've been wondering, is there any way to make lights flash on and off? Is there a way to make lights pulse like in a dance club? Is there isn't, I'll leave it at that, but if there is, it'd be pretty cool.

Lights can not be turned on and off dynamically. You can turn a light on, but it can't be turned off.

Oh...I see. Well, that answers that.

If it can't be done, why is the light in one of the Tantive IV rooms (barracks) flashing/flickering?

I just checked it out. There was flickering light emanating from the...erm...light, but there was no light source in the light layer. The object itself emanated light. So, I suppose you can create pulsating light if you just do so in a round about way.

You can only make lights flicker if you have a hardpoint on a model where you can attach a light, then set the flicker in the light's odf.

But it looks cool, I made a disco out of it myself:
http://www.xfire.com/video/47a998/

Really? Awesome! It's a shame I can't model though.

I'm wrong as usual.

Have a look at the BF2Lighting.doc that came with modtools you might get some ideas
You can attach a light odf to just about anything