Nice. Thanks for the link.

FYI: There is an “s” missing from the end of that url. https://www.ifixit.com/products/mako-driver-kit-64-precision-bits

Thought they might sell these specialty tools online, but 3 minutes of searching came up with nothing. Might be time to get creative.

Do you have the room to get a Dremel in there the cut it so a regular flathead will work?

If not, maybe try to use needle noise pliers as your screwdriver.

As a last resort, pick up a cheap screwdriver and cut it to make it slotted.

Edit: I love how quickly several people have commented with links to the needed tools. Thanks to all of you!