No check in for WWBA and other tournaments is required. Just coordinate with his coach and show up ready to play. All the check-in, roster finalization, etc. is done by the coach and/or online in advance. Individal check-in is only required for Showcases.
Edit: Here is the tournament link. This may be what you are looking for. Click around on the menu for teams, rosters, locations, schedules, etc. http://perfectgame.org/events/Default.aspx?event=2994