I don't think they exist, since the codes for these characters are above 255.
An "alt" (pun intended) way of handling the problem is to pick a nice font in Character Map, and cut/paste the characters you want into a text file. From there you can cut/paste them into documents, Textkit, etc. I do this with the New Athena Unicode font, since it has PUA (Private Use Area) characters for things like alpha w/ macron + acute accent, etc., that the Greek Polytonic keyboard can't do.
Or maybe there is a keyboard something like the Greek Polytonic keyboard for Latin?
OK, I was wrong. I was using NotePad, which apparently doesn't handle alt key codes above 255.
Using Character Map and with a nice font selected (I'm using New Athena Unicode), find a characters you want, and look down at the bottom for a number, e.g.
U+0100: Latin Capital Letter A with Macron
Convert the number from hexadecimal to decimal. Hex 100 = Dec 256
Hold the Alt key down and type in 0256, using the keypad, into an app like WordPad or Word that recognizes these codes.
Cut/Paste this to Textkit.
Sorry, best I can do.
I, Lex Llama, super genius, will one day rule this planet! And then you'll rue the day you messed with me, you damned dirty apes!