My husband's test took about a half-hour in the lab and I believe he was awake for it. They will give procainamide over a period of time (I think it's usually in an IV drip) and see if your heart shows an altered rhythm on the EKG. Brugada is a disease where the sodium channels in the heart don't carry what they're supposed to, and the drug works to mimic this effect, in my understanding (by blocking sodium uptake, I believe.)
They are NOT trying to induce a cardiac arrest in you. In a very very very small percentage of patients this happens (I think it's a lot less than 1%?), but that's not the goal. The procedure is done in a controlled lab with lots of equipment to get you out of cardiac arrest, in the slim chance that happened.
After the test you're pretty much ready to go. They'll watch you for a bit but I think you're up and out of there pretty soon afterwards. I don't remember much - someone else might know more and there might be posts on the board. They do this on children, too; it's not considered a high-risk procedure, at least according to our docs.
What doesn't kill us makes us stronger =]