To set the base timing on an EFI engine you need to bridge the diagnostic plug pins under the dash with a paperclip (pins 5&6 if memory serves correct)
Start the enigne and the engine light will flash on the dash to let you know its in diagnostic mode.
Then you set your base timing to 10 degrees BTDC (Some do it to 11-12 on higher octane fuels but I just stick at 10)
The ECU controls the advance curve in the tune etc so all you have to do is set the base timing and your set.
What you do need however is to take the car to a tuner, you can't run a 284 on the stock tune, just won't happen (if it does run it will run like ass, won't idle and probably do some nasty things to your engine), a decent dyno tune will set you back around $500 if you shop around, but anything more than a 268 and you need a tune.