We have released a new version of the Pololu AVR Library with a few improvements and bug fixes. The library now supports up to 16 QTR sensors at once. In the 3pi section, there is now an option to disable use of pin PC5 to control the IR emitters, so that you can easily use this pin for an additional sensor or digital output. Most importantly, we have fixed a bug in the batch file that was preventing installation from working on some computers.
You can download the library directly here. Please let us know if you have any trouble installing this version, and send us your comments and suggestions!