The users must of course be registered with nickserv before granting them +v (voice).

You’ll then need to set the XOP system off for your room with this command:

/chanserv set #YourRoom XOP off

Then use this command:

/chanserv access #YourRoom add NickName 3

Also have a look at the ChanServ forum unser the Epona Services category for more information on chanserv commands.