For any character for which a macron is part of a recognised language, you
should be able to find what you need via Insert|Symbol.
Alternatively, you could use an equation field codes as:
{EQ \s\up6(\f(,A))}
where
.. the field braces '{}' are created via Ctrl-F9
.. 'A' represents the letter or string that you want to process
.. you press F9 to see the results after the coding is complete.
Coding the field as per the above has the advantage of not increasing the
line spacing.
Cheers
