Please stop by my office when you get to the mainland and I can set you up with both.
What part of Guatemala were you wishing to get to? And what part of Honduras?
You can either fly or bus it to Guate, and to get to Honduras you would also need to fly. For either, you will need to return to the mainland either to get a bus or a flight. However, you can book both the bus ride or the flight right here on the island with us.
Hope this helps.