You need a Wireless router. I don't know much on Mobile Internet, but I know for sure that they aren't Wireless adapters.

Your Laptop needs to be connected to a Wireless router connection (preferably your own) to connect to Xbox Live as Xbox Live needs a direct Broadband connection.

So you would need to fork out some money on buying a Wireless router for your laptop (Cheap ones around $75
Prices range from $70 - $500) and then connect your laptop up to that and then connect your Xbox up via…

Either, Ethernet cord > to your laptop. For example,
Xbox 360 _Ethernet cable____Laptop.

Or you could fork out another $100 for buying the Xbox 360 Wireless adapter which would connect to your Wirless router via wireless (Without using laptop).
Your best bet is to buy a Wireless Modem Router for you home for which you can connect your laptop to, then connect your Xbox 360 up to via an Ethernet cord supplied when you bought your 360. If not supplied, you can buy one from an electronic store for about $25.

Sorry for your unfortunate situation,
Take Care ?