The 'quickest' way would be to use some data aggregation tool, like Flume or Chukwa. You can find a very good example on how to collect Twitter data through Flume using Twitter API here. It shows how you can use Flume to read twitter data into your Hadoop cluster and then process it using Hive. You could write your own MR job to do that if you need that. Trying to devise a custom InputFormat for these kinda things really requires some work and I don't think you'll find much help on this(Unless somebody has done this and is ready to share it with you).
HTH