Originally Posted by gchild
Is there a DIY guide you could kindly point me to?
if it goes wrong or doesn't look right, is it reversable?
Only guide on here is for removing and installing the trim: http://www.e90post.com/forums/showthread.php?t=137527
If you search you could find a more generic guide, its pretty straight forward though. Only real issue is to make sure that you line up the pattern on different bits of trim.
Is easily reversible, just pull it off. Even possible to reuse the bit of vinyl.