You can import it, but since MP4 files don't typically have timecode, it might be problematic come online. I did a test a while back where I imported the clip and the Avid assigned it a starting timecode of 01:00:00:00 and then I AMAed the same clip and transcoded it, in that case the starting timecode is 00:00:00:01. The issue being, come online, if you batch import you'll have to batch import the entire 2 hour clip at high res.
I'd recommend using MP4 to QT (http://www.videotoolshed.com/product/66/mp4-to-quicktime/3)
That will convert it to MOV with timecode so that you can AMA and transcode. Edit to your heart's content. Then you can relink to it for online and just transcode what you need.
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