I have done quite a few prototyping using QFN chips. And here are just a few examples:
http://www.kerrywong.com/2010/10/24/rf-data-link-using-si4021-and-si4311/
http://www.kerrywong.com/2010/07/16/an-arduino-compatible-using-cp2102/
http://www.kerrywong.com/2010/04/16/interfacing-lis3lv02dl-using-spi-i/
In the last included link, I briefly described the technique I used (actually, nothing fancy). Anyway, it's doable.