Is it possible to type in macron (e.g. "ā") without using U.S. Extended Keyboard?
Solution 1:
Keep US Extended and use it to type your å. It's alt + k and then a.
Solution 2:
This is just a option without changing the default Keyboard.
In OS X, this can be accomplished by holding down the A briefly and a pop-up will appear.
Just select by clicking or typing the corresponding number. In this case 8
ā ← Like that
The repeat delay can be set to prevent eeeeeeeeee from happening too quickly.