Start by acquiring a shiny C5 Corvette!  Have some jackstands, a floor jack, a mechanic's creeper and some wood blocks handy.
 

Lay out your wooden blocks.  When you drive up on them, you will provide enough clearance, at the front of the car, to roll the floor jack underneath.

Drive up onto the wooden blocks.

For safety, put the transmission in park (1st or Rev for manual) and apply the hand brake.

Insert the liftpads that you made.

Slide the floor jack into place, allowing the pad to contact the front cross-member under the front of the Corvette.  Be sure to straddle the 2 rails on the cross-member to prevent damage.  Also, be careful not to allow the jack's pad to come in contact with the fiberglass transverse leaf spring immediately behind this cross member.  Note: You might need to put a block of wood on top of your jack pad just in case you can't lift the C5 high enough to put jackstands under the lift pads.

Place the front jackstands under the lift pads and disengage the jack.

Next, move to the rear of the vehicle.  Place the floor jack's lift pad against the rear-most cross-member.  Chevrolet recommends that you jack the rear of the C5, on the crossmember, but only where the A-arm meets the crossmember.  In my picture, I am jacking on the center of the crossmember, and have done so without doing any damage.  Other C5 owners have jacked in the center of this crossmember but only after placing a large block of wood or a 5 pound steel weight on top of the jackpad, displacing weight.  No matter how you choose to jack the rear of your C5, be careful not to allow the jack's pad to come in contact with the fiberglass transverse leaf spring immediately in front of  this cross member.

Then, place the rear jackstands under the rear lift pads and disengage the jack.  NOTE: reverse this order to put the Corvette back on the ground.

I wanted to include this picture.  This is what a 100% rubber hockey puck will do when the weight of your C5 is applied to it.  This is why I prefer to use 2 pads instead of one.  The points on the top of my jackstand would have come in contact with the underside of my car or it's body.  Notice the 'dotted' grease marks on the body.  This is where the dealer last lifted the car at their shop.  The GM lift pads are not tall enough to properly accommodate the dealer's lift nor a jackstand.

The rear set of pads do not support as much weight as the front.  Thus, there is less distortion of the rubber.  After use, the lift pads return to their normal shape. I've also been informed that orange training hockey pucks can be used as they are harder and hold their shape better than official black pucks.