[XeTeX] Grave accent character U0060 in XeTeX?

[J P Blevins]

I hope that this is not too far off-topic, but can anyone suggest a  
strategy for printing a grave accent character (not as a combining  
diacritic) in XeTeX. I realize that this is a more general TeX issue  
and that the character is not used in typesetting, but it is used in  
the Finno-Ugric IPA, and the smart single quote alternative is used  
with an opposite meaning ...

I would be prepared to give up the use of ` ' to enter single quotes,  
if necessary, but it would be nice to be able to represent the smart  
quote in the text font (Aldus nova, in this case).

Thanks in advance for any suggestions.

  Jim