the easiest way is when the ps3 is dissembled, no need to cut anything, u could do that to make a perfect fit if ur doing a perm-install of the e3 flasher, e.g a CECH2004, those are the b*tches of um all(NOR's) i cutted the alu plate...then a guy posted a picture of the e3 ribbon going over the HDD slot...much better and no cutting required
BUT if perm-installed WATCH IT when put together..the ribbon get's easely smashed/damaged from the aluminium plate..so be carefull