To begin, we start with actually possessing a can of BLO, because without the actual can, then we can't actually open it, now can we. If I count this as a step, then it would be 5 steps and I would have to change the title of this post, so, moving on.
Step 1: Remove the plastic Cap. Revealing the metal cap underneath.
Step 2: Remove the metal cap to get to the pesky paper seal type gasket on the spout.
Step 3: Remove the pesky paper seal type gasket off the spout. Alarmingly you discover there is still one more step, the metal internal cap/seal/thing.
Step 4: To remove the metal internal cap/seal/thing, stab it with a Leatherman, or any near by sharp object, and pry off.
That is how I open BLO.
At this point I am just glad that the lid wasn't childproof.