How to set AirPlay device name of the hosting computer?
Here's what I did to rename the Computer label in the list of available AirPlay speakers in iTunes.


In Finder, go to your Applications folder.
Hold the control button and click on the iTunes icon. You'll get a pop-up menu.
Choose Show Package Contents from the pop-up menu. You should now see a Contents folder in your Finder window.
Use Finder to navigate to the Contents > Resources >  English.lproj folder.
Open the Localizable.strings file in a good text editor.

You may want to make a backup copy of Localizable.strings before going any further!  

TextEdit isn't good enough. It'll show you gibberish. I used TextWrangler, which is free.
Use Command+F to search for pb7r8smvm5. You should see two lines that look like this:


  &lt;key&gt;pb7r8smvm5&lt;/key&gt;
  &lt;string&gt;Computer&lt;/string&gt;
  Change Computer to whatever label you want (e.g., Living Room).
  Save the Localizable.strings file.
  Quit iTunes and then open it again. Your new label should appear in the list of speakers.
  
  These instructions are for Mac OS X. Windows instructions are available.