Well, if you need it badly enough to dare to modify a couple of sacred core scripts,
really IMagick is used only in two places:
oc-includes/osclass/classes/ImageResizer.php
oc-includes/osclass/classes/Watermark.php
And this is an alternate way to use ImageMagick from PHP:
phMagick requires 2 things ImageMagick and the ability to issues systems calls with the exec() function
phMagickNow, obviously this won't have exactly the same syntax than Imagick, so you'd have to learn a few things to achieve your goal (but not too much, truth is ImageResizer.php is not so big a script).
Regards