N-wireless range expander connection

[dsalvail]

My old man (a MAC fanatic) has just purchased a Engenius N-range expander (ERB9250), to get wifi internet access from his home into a remote garage where he gets some peace and quiet from the old lady. Can't connect to the MACbook, no matter what he tries.
His laptop sees a signal from his router, so I figure that's not where the problem lies. It's either the router-expander connection, or the expander-laptop connection. I advised him to simply reproduce the laptop's config into his expander, but he can't open the web-based config windows (192.168.1.2, or .2.1, I forget, but he knows.)
His there a trick to getting into that window? My experience with Linksys and DLink was relatively easy. Do you suggest another approach? he can't recall whether his network is protected; is there a way to give the expander the username and password his laptop uses, or will the expander take on the config of the wireless router, and then ask the information from the laptop at the moment of connecting?

I know this is kind of remote; thanks for your help, through me, to an old man not very versed in the technology.

DS