I've always jacked up my other car by putting the jack on the recessed spot for a jack underneath the engine cradle. Proceeded by jack stands on the control arms. Never looked underneath my Vette yet, it's too new lol.
first off you need a low profile jack, i bought an aluminum race jack good for 2 tons for $99. you then can slide the jack under the front of the car, there are two parallel beams, you want the one more towards the middle of the car. place a 2X6 between the jack and the cross beam and lift. you can then place 2 jack stands on the perimeter where there are recessed and use a hockey puck to prevent damage to the frame. work your way to the back of the car, again lift the more middler beam using a 2X6 as a cushion then place your remaining 2 jack stands. if desired i can put together an in depth DIY for this as i have neevr gotten a clear definitive answer.