I've never seen that before. Is it because they're under-rated weight-wise or something, or don't have very stable bases? Most of the standard jack stands available at auto parts stores or Sears or whatever work fine for holding up all 4 corners of the car. You do have to be careful about placement though: they need to be placed somewhere that they can seat solidly, and that's design to carry the car's load and not damage anything.
Somewhere on these forums, someone showed how to mod a hockey puck so that you can use the "edge" mounting points that were designed for the trunk emergency jack with regular jacks/stands.
Personally, I set my front ones as far forward as you can go on the two main frame rails under the car just before they curve upwards (these are the obvious wide pair of solid metal beams running the length of the car, considerably inboard from the outer edges), and the rears on the rear suspension arms (like you can see in over here in this swaybar install thread:
http://www.the370z.com/diy-section-d...tion-rear.html )