The only way to do this is to move them to the project timeline and make any necessary edits (if needed), then share with iTunes. You are correct...you cannot share from the event timeline. This takes very little time. I do this myself with our iPhone or Flip videos. These videos are available in the event timeline in iMovie and within 30 seconds I can have them in the project timeline and shared with iTunes.
There is no way to play back 'raw' camera footage in iTunes, unless somehow your camera records footage in a format that iTunes can natively display. In which case, you could probably just drag the files like you said originally from their location on your HDD to iTunes. I suppose you could just try that and see if iTunes will natively play them (although I assume you already have tried this or you wouldn't still be asking how to do this). There will be no translation of the file within iTunes though, so if it doesn't play, which I assume it won't, you need to use iMovie.