Nomad,
Go to your Honda dealer and ask him to copy Honda Publication Mll 12946. This publication shows the adapter clearly and should answer any questions you may have. The price of this unit is quite low (by Honda standards) $75.
I went the MoTech route--which is more expensive--actually twice as much, but I wanted a luggage rack that could accommodate a variety of cases, be they CooCase, GIVI, or whatever. The luggage rack snaps off in a second and the new adapter snaps in. For the time being, I am happy with the AluRack setup since I am not in the market for a hard top case. I am perfectly happy with the soft luggage carrier which will handle a wide variety of waterproof duffels. Hope this info helps.