This has been done to death, but there still seems to be a lot of confusion about it. If you are a new joiner, you can take the allowance regardless whether you rent or buy. If you are already here, you will only receive the allowance once you have purchased a property in the UAE. There is no option to rent and probably never will be again I imagine.
If you want it that badly just buy a cheap studio somewhere, live in it for a while then move out. The rental returns on it are good.