Yupp, it’s possible. Just go into Bluetooth settings and pair both devices.
Although I would recommend playing the iPod Touch through USB, since you’ll probably leave it in the car most of the time and take your phone (Blackberry) with you. Then, the iPod will play through USB and get charged and your Blackberry will be the only Bluetooth devices available to ring and make calls.
That said, you should just get an iPhone and get it over with