Perhaps you could import via TWAIN in the past, but even photoshop (annoyingly) has had that feature removed now. However, you wouldn't want to do that in Illustrator if you could — bitmap (raster) images should be treated (suitably sized, any colour correction etc) before importing to illustrator. Don't do anything to bitmap images in Illustrator other than position them.
Just use OSX's Image Capture to scan. You can then resize etc in Photoshop if you have it (if not just use preview) then 'place' that file into Illustrator. If you do have photoshop, you should ideally place the file as a PSD which you can keep editing and updating from photoshop.