I have never changed lighting so I have no clue how to do that.
When I went from PC's to T5's i cut my light cycle in half. So if you normally run your PC's for 8 hours, you'd only run your T5's for 4 hours in the beginning, and so on. You can add an hour every week until you get back up to 8 hours (as an example).
Some folks will keep their lights on for 8 hours (as an example) but they will go the hardware store and buy some of the window screen (that keeps the bugs out when you open your windows at home). They'l cut it so that it hangs over the tank enough so the weight doesn't droop the screen into your water. This way they can still run their lights for the full 8 hours, but the screen will "screen" the light. tyou can take one screen off a week until they are all gone and your'e at full light.
Personally, if ou don't mind having your tank off for half the day, it's easier to just cut your time in half and gradually build up.
Most important is to keep an eye on your corals and make sure they are not getting distressed.
