Rockbox

I don’t know if exist some solution for spelling of special character for Voice output.
In language files is only this for standart character A to Z :

<phrase>

id: VOICE_CHAR_A
desc: spoken only, for spelling
user: core
<source>
  *: ""
</source>
<dest>
  *: ""
</dest>
<voice>
  *: "A"
</voice>

</phrase>

Is it possible add next phrase for next char by using utf-8 codes.
He re is my example :

<phrase>

id: VOICE_CHAR_UNICODE_017E
desc: spoken only, for spelling
user: core
<source>
  *: ""
</source>
<dest>
  *: ""
</dest>
<voice>
  *: "ž"
</voice>

</phrase>

In each language file should be add only necessary extension characters.

It would be very great for blind users of RockBox.