Yes, I just did it, without removing the mounting plate or the axle. You have to remove the two pins that the caliper floats on, the upper left one comes out rather easy. The upper right one...not so much. They're #9 & 11 in the linked picture below. No. 11 has a small rubber boot(#10) over it that runs through the entire hole it's mounted in so don't try to pull it out. Look closely at #11 and you'll see it is threaded with lands on it for an open end wrench. I believe it's a 12mm wrench but just try it to find out for sure. Before messing with #11, remove #14 and remove at least the outer pads. I'd also compress the pistons first, might remove some fluid from the rear reservoir down by the foot peg first....then remove the outer pad(I also removed the inside pads for more wiggle room). Then back out #11, with the pads removed that should give you enough wiggle room to lift the caliper off the mounting plate and rotor, fully exposing it. If you aren't concerned with loss of fluid, then before doing any of the above just remove the brake hose and stick a bolt in it to keep it from dripping all over everything. Then when you accomplish the above, you can completely remove the caliper without pulling the axle or the thick mounting plate. Keep in mind, #11 won't come all the way out due to the boot. It will come out far enough to get the caliper off....be patient. Don't replace the pads until you get the caliper back in place and #11 at least started. Hope this helps.
http://www.valkyrieriders.com/shoptalk/GL1/gl37.jpg