How do I open my 50Gb of GoPro footage in iMovie?

Last week whilst snowboarding, I took out my GoPro HD Hero 2 and collected a few hour's footage each day.

I now have around 50Gb of footage in 720p/60fps and would like to edit it in iMovie '11.

I think this is a pretty simple request. What the Merry **** am I meant to do?

I expected to be able to browse to my external 4tb hard-drive within iMovie and see it sitting there ready to edit. Apparently not.

I then clicked on 'import' on just ONE folder (it's divided into five, Monday-Friday) and it took two hours to 'import', then won't even turn up in the browser anyway (even I can see hideously large .mov copies of these files in Finder.

Why on EARTH should I be doing anything more than browsing to my footage on my external hard-drive and editing it straight into my film?

What am I meant to do?