The hyperdeck - even when configured at its maximum compression settings -still records at a very high quality (bit rate) of 220mbps. So on a 240gb drive you will still only be able to record about 2 hrs of video. Is that enough time for your event?
This is using either the prores or DNxHD codec that you configure using the hyperdeck setup utility that you install on your pc/Mac. When you run that and connect the hyperdeck using a USB2 cable you can then choose the codec you want.