Context Reaction: Theme 7.x-1.x-dev

Unworking: Drupal 7 upgrade of http://drupal.org/project/context_reaction_theme.

This is a clean upgrade of the D6 version of this module. All of the context-related functions work, however, I cannot get Drupal to listen to the value of $custom_theme (set in $plugin->execute, called from the hook_init()).

I also explored using hook_custom_theme(), like themekey does, however I was unable to get the plugin to load from this hook. It seems like it is called earlier in the bootstrap process than even hook_init().

Are there any more ideas out there?