Audio line in while recording with ipod touch

Looking at buying a 5th Gen touch to record local basketball games. Need the ability to record the audio live broadcast into my live video of the game so I am wondering if I can use the video camera of the touch and record a seperate audio track with the video being recorded with a line in option. I have used a sd camcorder with a line in capability playing the local radio station audio as I record but dont know it this can be done with a ipod touch. I could use the camera app or imovie app to record but not sure if separate audio track is possible with them or will it just record from the mic of the ipod touch?