The boot clamp does not require a BMW tool. It just needs a standard CV boot click pair or pliers. You can get them at most part stores.
Ask for CV boot clamp pliers. 
Here is a link to a set of DIY instructions. I think these are the ones I used.
https://www.xoutpost.com/articles/x5/suspension/19124-cv-boot-replacement-diy-bmw-x5-e53.html
Post time: Jul-13-2017