Create custom item type

Can you post the module you wrote here just as a zipped up file? I'll take a look over it and let you know.

I'm not completely clear what your question is. You shouldn't have to save the checklist item instance. The API should do that for you. You just define some additional fields as needed for your new item type.

The function checklist_pro_checklist_item_user_like_us_display_options($instance, $item, $account) returns the path that the checklist item links to: checklist_pro_like_import. This path however is not in your list of allowed urls returend by checklist_pro_checklist_item_user_like_us_allowed_paths($instance, $item, $account) (Actually it looks like you haven't set that function up yet). So you need to add that path. When a user clicks the item, it will go to that path and you should then check if they've completed the facebook instance. When you hit that path, checklist_pro_checklist_item_user_like_us_process_item($instance, $item, $account) will be called and that is where you should check if the user has completed the item, and if so you would return TRUE. If they haven't, then you could setup that path using hook_menu() to display a page to say something about liking the required page on Facebook.

Hopefully that will get you moving more in the correct direction.

It is used when limiting navigation but it's also used to check if the current path is the one for one of the checklist items. Good luck. Let me know if you have more questions.