Add module-generated pages to Drupal 7's search index
Implement hook_search_info() to describe your new search type.
Implement hook_update_index(), build up the content you wanted to be indexed, and throw it over to search_index() (see the example in hook_update_index()).
Profit.


Be sure to follow all the advice in the comments in the linked functions, and check out the core node and user modules' implementations of these hooks for examples of exactly what you need to do. The comments for hook_search_execute() should also prove pretty helpful.