You could try scrubbing it flat on a piece of smooth concrete. Then go on to emery papers to smooth it off.
Some people now a days actually say you don't need honing oil, unless you already use it on that perticular stone. They say a new dry stone won't load up. I don't believe them. I have used WD 40 before, 10W30, transmission fluid, 3 in 1 oil, Kroil penetrating oil, and even gun oil. I have liked gun oil the best, Marbles gun oil to be exact. Kano Kroil penetrating oil also seems to worrk fine. I only use arkansas stones too. These oils can destroy a synthetic stone. When I am desperate I will spit on my small arkansas honing stone, or dip it in water.