The brackets should have been included with the calipers otherwise they wouldn't have been able to mount them at all. Were they new? or used?
if used i bet you have a seized caliper and will need to buy a rebuild kit. otherwise you have some dumb mechanics because there isnt much to it. If the pads are locked on to the rotor then how did they get them on there? take a c clamp and slowly push the piston into the body of the caliper. mount the new pads, then mount the caliper onto the spindle/axle. Its not too hard. Bleed the brakes and it should work fine. There is no way they wont fit under a 16" wheel.

if you have any questions reference my install here:
http://home.earthlink.net/~djtrickee/GSXBRAKEINSTALL

P.S.- this is why i do things myself- you know exactly what is going on and how things work!!