How to select the selects
One issue I handwaved over is the fact that if Aperture can’t render the RAWs you can’t view the image. They thumbnai somewhat okay (delta losing rotation data), but you can’t view it.
One approach is to use Derick Story’s “New Version from Master JPEG” trick, which works great for preview, but you end up with a second image, and that image is a JPEG, not the RAW.
My approach is to just view the JPEGs as an icon preview in Finder (largest size) and then hitting space-bar (quick look) a lot. It’s very cumbersome but gets the job done. You can also use the largest thumbnail in aperture you can get away with in Aperture.
The other trick I’ve found hinges on the fact that the E-30 and the E-Px series use the same RAW format. someone wrote an Applescript that will rewrite the ORF metadata to an E-30. This will deceive Aperture into importing the image just fine.
The issue I see is that the camera data is wrong, so there is no distortion correction in your images. Also, if Aperture decided to support E-P1 in the future (and they will, because these cameras are popular), then you will not have any lens distortion fixes available even if you regenerate the RAW version. But at $7 it’s worth a try—it’ll be much easier than running exiftool on your own.
Then there is an old trick of modifying the Raw.plist that I used to do with my Panasonic LX1. It turns out that Apple has made it exceedingly complicated. Added to the mix is that the “EP1” is three characters and the only other three character Olympus RAW is the E-30 which is the base RAW for the translator! If you figure out how to get it to work though, I’d be interested in how.