Check pictures you can find online for placement ideas - eyeball the placement - put masking tape on the bass and position the bridge cover on it carefully. Make sure that neither the strings nor the bridge can touch the inside of the cover, then mark the bridge position and the mounting holes on the masking tape.
Remove the bridge cover, double-check that the mounting holes are as level as you can make them, sit the bridge cover in place one more time to confirm that it all works, then drill. If in doubt, drill smaller than needed. You can always make a hole bigger.
Remove masking tape after drilling, making sure NOT to pull up any paint chips.
When inserting the screws, rub the threads along a bar of soap or paraffin and they will go in much more easily.
That's how I mounted the bridge and pickup covers on this bass: