Believe me, it will be MUCH harder to "try to get that to work" as opposed to getting some 2x4's and/or 4x4's and putting them together for a new stand. If you get your measurements then any hardware store can cut the wood for you. Then you get some screws, maybe some brackets, and go to town on putting it together. If you get the pieces cut by the hardware store then you can probably have the three level frame built in under an hour, if you use a drill screwdriver.
Please just take our advice and ditch the shelf. Isn't that what this thread is about...didn't you ask if the shelf can handle the weight of the tank? Since we are all telling you (notice that not a single person has said that this is ok to use) that it's not safe, please listen to what we have to say. I know it's not what you want to hear but it's the truth. The shelf is great for keeping lawn tools and random crap that's not too heavy on it but it's not at all designed, nor is it capable of holding the weight of aquariums.