where do you mount your 530t?

3M heavy duty double-sided foam tape -- i used that stuff to attach my lip spoiler onto my ride and it's been SOLID (exposed to all the elements, etc), it'll be a no brainer for your application.

Mount it to the inner side of the door panel or something with a very/faily flat surface so the tape adheres properly.  Make sure it's clear of the window's path of descent.