Hi travelmad! Just how "travel-mad" are you?
If you're pretty mad, and have time, here's another idea that will allow you to exchange 5,000 Membership Rewards for an inter-island ticket.
1. Set up Continental OnePass account.
2. Transfer 5,000 from Membership Rewards to Continental.
3. Set up Amtrak Rewards account (Free).
4. Transfer 5,000 from Continental to Amtrak. This step can take weeks.
5. Transfer 5,000 from Amtrak to United.
6. Redeem 5,000 in United for Aloha airlines inter-island award.
There might be a faster way, but after a quick perusal of membership rewards, that's what I came up with.