I noticed in the datasheets that the 3pi has i2c pins but are inaccessible to the user. is there any way to get around this? I found descriptions saying that the orangutan can let us access i2c pins, but if we just have a standard 3pi is there any way to access i2c?
Unfortunately, short of removing components, you will not be able to access hardware I2C on the 3pi. The I2C/TWI pins on the ATmega168 are PC4 and PC5. PC5 can be made available by removing the jumper between it and the IR-LED-controlling MOSFET, but PC4 is hard-wired to the output of the right-most line sensor. You will either need to use software I2C on the 3pi, or you can set up your 3pi as a serial slave of another microcontroller that has its I2C lines available.