The DME for E30's (at least my car anyways) is located in the glove box. You have to remove the upper plastic pannel to get at it. Also you probably won't have any torx screws that need to be removed (my DME only had tabs that needed to be bent up to remove the cover)
Yeah it is located in your glove box, you need to unscrew 4 (10 or 12mm bolts ) and bend the metal cover clips to open. Depends on the DME (car model) some are made from 2 PCB boards on top of each other....if you have that one you need to separate them in order to access the chip.
The main connector may seem to be stuck, you need to unscrew the the DME first and than remove it at an angle.
If you got 2 PCB boards stacked you might want to take time with it. Top board is held tight by clips and only way to separate it is from "main connector" side with screw driver.