Now please, don’t

• believe it’s difficult
• watch the screen when typing numeric code
• type the 4 digits too hastily
• press Ctrl key [bottom-right] instead of Alt key.
• press AltGr [bottom-just right of space bar] instead of Alt key.
• hit Enter just after having typed the 4 digits

There are other methods, for example at langue-fr.net
Our method has two main advantages:

• it’s easier to memorize, for you get every characters the same way
• it works on more than 90% of the keyboards

Is it required to accentuate uppercases?

Yes according to l’Académie française. Much more info in this article by Jacques Poitou.
À notre avis, --in our opinion--, accents are valuable:

• French words get their full meaning out of them
• they’re nice and catchy
• you already like ’em, don’t you?
  • à la ...
  • cliché
  • déjà vu
  • exposé
  • outré
  • risqué
  • touché!
  • vis-à-vis
  • et voilà!

Ethan Cætera