Hello,bvl:
What is your system? Windows or Linux,or others?I just have configured it under windows xp successfully, I think I can help you if you use xp!
1)download qt.exe
2)double click to install it!It will be install in "c:\qt\4.2.1"
3)Add "c:\qt\4.2.1\bin" to the environment variable Path!
4)restart will be ok!