Use default installation profile?
This part of your original question isn't quite clear:


  Simply setting it as the default selected profile is not enough.


However, all you have to do is to add exclusive = TRUE in the .info file of your installation profile.
This will automatically select your installation profile, and the user will proceed to the language selection screen.

Note 1: the setting above will be ignored if there are 2 or more installation profiles marked as exclusive. This might happen only if you downloaded another installation profile and are keeping it in the /profiles folder (e.g. Commerce Kickstart).

Note 2: this has been committed to Drupal 7.22 and is based on this issue/discussion.