I doubt you can cut it, but I have no experience with that stem. Most of them are either of the sliding wedge (you'll see it cut on bias at the bottom with matching bias cut on the wedge) or cone wedge (little cone guy on bottom of stem bolt tightens up into bottom of stem body thus spreading stem) and it would be a nightmare to attempt to shorten either. Nitto makes a swell 58 degree track stem with very little left inside the steerer tube, but its about $75...it is quite stiff to boot.
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Rock Lobster