You can shorten it by a couple mm each side, me I went 5mm each side, if you do that you will also have to shorten the spindle bolts as well but be careful if you decide to do so as the Allen only goes in so far and what I mean by that have a look at the 10mm Allen and where the thread is and you'll see what I'm talking about , I've done it myself and it's nothing to worry about.
If you can chamfer the edges it will also help with installation, just a quick grind and or file will do the trick and a little bit of fine sand paper to finish it off.
Obviously you'll want to get the cut as straight as possible otherwise when installing sprocket or crank you can have a hard time and depending on the work done could cause problem but a little bit off won't do much mainly if the work is haggard.
Or you could just pick up a 22mm stolen spindle with some 15x1mm accompanying spindle bolts to go with it from Dans for $40 if your not up to modifying.