What you need to do, is find out the MAC address of your XBox. It will begin with either 00:50:F2, or 00:0D:3A.
This is what you'll put under "REAL MAC". You'll need to have the XBox on, and looking for system link games (CounterStrike will work fine, just let it search for system link games). Most of the time, the XBox's real MAC address won't appear until there is a wired connection from XBox to router or what have you. This is what flat235 (TD) said for you to do, but you said you can't access the router in the hotel.
This is basically your problem I believe. You need to hook up the XBox with a wired connection, so that the XBox's MAC address appears in the list of 'Local Visible MAC Table'. You *may* be able to see the XBox's MAC address without wiring it first, but I find it unlikely... Should you be able to select the XBox's MAC, you now have to know the MAC address of your Wireless Gaming Adapter that you are using for the XBox. You may be able to find it on the actual device on the bottom or something like that. Select this as the 'Nominate WET11 MAC' box.
Close the advanced settings box down, and close XLink down by right clicking the system tray icon and hitting Close. This is the only way it will save your settings.
I highly suggest that you avoid using Bo-XLink until you confirm that you can get everything going and play games just using XLink. Switch over once you confirm you get it working.
I don't know how much we can help you, as you don't have access to the router, and you are unable to manually type in the MAC addresses. Give it a shot anyway...
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