Well, I've been trying to install ParaView for a while on Snow Leopard, and I was unable to do so since the installer for the current version of the Qt SDK (4.5.2) is broken. However, not all hope is lost. The installer still contains everything necessary to get Qt up and running. Here's what to do:
First, open the package and mount it by double-clicking it. Cancel the installer that pops out, and go into the Finder, and open the Qt SDK image. You will see a "QtSDK.mpkg" icon, like shown below:
Right-click on it to reveal a context menu, and select "Show Package Contents", which will open a new window with the innards of the installer:
Not very exciting, but it will suffice. Go into Contents/Packages and you will see the motherlode:
Now, each .pkg file contains its own installer, which you can activate by double-clicking on each of the icons. I installed the libraries, debuglibraries and headers packages first, then everything else. Now, if the installation was successful, we should be able to go into /Developer/Applications/Qt and see if the qtdemo program exists. In my installation, it did, and when I executed it, the following screen came up:
I haven't tried playing around with it very much, but the gradient and vector deformation demos do work. Now I just have to try getting ParaView to work, but that'll be later...