Sorry just reread #1 and noticed two things I missed yesterday. To clarify, you don't have to go through immigration to transfer, but you do have to do security of course. Arrive lower level, go through security and work your way upstairs as in many places. This is available in the satellite concourse where you likely will arrive.

And the other thing I was thinking about is you mention luggage and interline, but I didn't think at first about checkin and getting a boarding pass. Maybe being able to interline implies having a boarding pass and being checked in already. But if not, and with Hawaiian being a bit smaller, you'll have to find a place that will allow the transfer or get boarding pass in the transfer area. Since HA are smaller and just that one flight a day to ICN, finding ability to checkin within the concourse/transfer area might be more difficult; so if you can't find a place to check-in and get a boarding pass (either in satellite concourse or main terminal), or if you can't do OLCI on int'l HA itinerary, that may be difficult and they might make you proceed to #2.