In order to access the internet through the Facebook Login asking for a Like + Check-in, users have to follow these steps:
STEP 1
User access to the Splash page and click on Facebook authentication button:

STEP 2
At the first access user allows or not the application to retrieve public information:

STEP 3
At the first step, user is invited to Like the page:

STEP 4
Choosing to Like or Skip the page, user is logged on and is able to surf the Internet.
NOTE
Check-in is required only next time user comes back to your Splash page and only if he has already liked the page,
therefore the ckeck-in will be ignored until user will Likes the pages.
STEP 5
User returns to the same Splash page and, if he liked before the page, the check-in option will be proposed

STEP 6
If the check-in is accepted, he should post a message

If the option is skipped, the check-in will be proposed again at the next login, according to Check-in settings in Splash Page.
Related article
Facebook social actions overview