Hello chaps downunder, given the nature of your problem I have to say I am with you both on this cane toad thing. Although I usually adopt the 'live and let live' attidude to most creatures I will go after something when it becomes a real threat and a pest. We live in the country and at one time we had more than our fair share of rats due to a smallholding farming activity nearby (gone now thank goodness) and we took to shooting them in the end. I drew the line on em when one got into our loft, we figured out where it was coming in and it was climbing a cable which ran up the side of the house. As it would do this in the middle of the night we were unable to catch it in the act so I figured out a cunning plan to get it.
I wrapped two pieces of silver foil around the cable, spaced so the rat would straddle them as it climbed up. I dug out an old security lamp with an infra red detector fitted, removed the bulb and hooked the lamp terminals up to each of the pieces of foil. Having stategically placed the infra red detector adjacent to the foil wrappings around the cable, I plugged the thing in and left it. Sure enough, the following night there was a loud crack accompanied by a slight fluctuation in the house lighting. I never found the rat but if it survived, it certainly never returned and we have been rat free ever since.
Whilst I don't like being cruel to animals, this seemed the only way to deal with the problem because if the rat died, that would solve it immediately but even if it survived, being very smart and astute creatures, it would certainly think twice before climbing that cable again!
Perhaps there is a method for dealing with your cane toads here. I assume they are nicely conductive, in the electrical sense, and if you could find something that only cane toads like, you may be able to rig smething up and blast the little beggers. The biggest problem is in creating something selective.. which only kills the toads and nothing else but I guess you've got better brains than mine out there who have already looked at this problem.
Good luck chaps, don't get tennis elbow with all that bat swinging!

Best regards..... Chris