Not OP, but I have a Mac and use the "ABC - Extended" keyboard, which has a full set of diacritics. You type them by using the option (⌥) key and a letter to set the diacritics and then type the letter.

    ⌥u  e = ë

    ⌥w  e = ė

For example, the key sequence required to type Kayodé is:

    ⇧k  a  y  o  d  ⌥e  e

etc.