Hey Florent!
You should indeed be able to add this function to show the ticket form for a specific event:
<?php tribe_get_ticket_form(); ?>
Now, it’s important to note that this is not officially supported for use on other parts of your site – so there is no guarantee that for your specific customizations, the tickets will still work fine in terms of being able to buy them and such.
If you find this to be the case, and need more complex customizations, then unfortunately you will have to code your own solution 🙁
Let me know if the function above helps!
Cheers,
George