I'm not sure of what you're asking. Did you install Parallels into the /Applications folder? It should be accessible to all users from there. Or is it that the folder containing the actual virtual machine file isn't accessible? If the latter, you can change this location using Parallels preferences. Change the location to a folder available to all users (as a sub-folder to /Applications, for example).
You can also toggle the file access privileges by clicking it and choosing Get Info (Command-I) and changing the Sharing and Permissions item (I think everyone has read/write permission, though).
If that's not what you're asking, please help me understand...
