As ghetto as it sounds, I used two scissor jacks on my car when I swapped the tires. (My father was borrowing my 3 ton jack, and I had 2 compact jacks from Dodge Neons).

It worked fine as the car was on the jacks for a day as my buddy swapped the tires for me.

Would I have worked under the car? Absolutely not, I just raised both sides enough to remove the wheels. Wasnt worried about it, the car was just sitting in the garage.