Will it be possible with guppies, no offense but I don't think they are the most intelligent fish. I've seen it done with larger cichlids (theres a great video on youtube where an oscar has been trained to swim through hoops). Though the practice of making fish jump has been discouraged through fear of the fish hurting themselves.
Luckily to train any animal, it doesn't need to be that intelligent, just active and greedy. It defiinately can be done with guppies as I know of several instances where they have been trained and also seen film of it too. Another trick I have seen is to get the guppy to jump over a matchstick floating in the water - like a bar jump. So it should definately be possible. Good luck with your training. It will help to keep the fish on its own for training and also you will have to divide the food up into absolutely minute little rewards - so it can have several rewards before it gets full.....