A small air compressor will probably work fine as long as the hose is big enough. I use one of these along with an air impact gun to change my front and rear sprockets, and never had trouble getting the front sprocket nut off:
http://www.sears.com/craftsman-3-gal...p-00915310000P
The small coiled yellow plastic hose that comes with it won't work with an impact gun, but a normal size 3/8" hose works fine.