¿How to change the rubber thing of the 3ds XL stick

Hi, well, my 3ds XL lose it's gray rubber Beneath of the rubber it's nothing than the stick itself. I wanna know if i can USE a CIRCLE PAD PRO XL rubber to put in my 3ds XL? (i CANNOT find the replacements). Then, how i change it? I have to open the 3ds xl for its back and remove the stick, and put the rubber or i dont even have to tak apart the 3ds i just put the rubber with... i dont know glue? i have no idea...