Thanks for all the replies and information! Sounds like a long gun shouldn't be too hard, so long as you already have the permit to acquire. Once I have the firearm shipped to my home, I need to bring the following to HPD to register it:
Unloaded, cased weapon
Permit to acquire (general long gun or individually issued pistol)
FFL
C&R book
Shipping slip/receipt of purchase
From the above replies, I also see that a C&R-eligible 12 round CZ-82 pistol would be denied a permit to acquire, since it exceeds Hawaii's 10 round handgun magazine limit. Guess I'll have to keep that on the backburner for now
Thanks again for the help.

I have spent the last few years in Florida and Texas, so all these regulations are new to me.