You can buy a router. Or disconnect the ethernet cord that is connected from your modem to your computer and put that one in your xbox then put it back when you're done.
I probably should have explained this better. The ethernet port and the console are on different floors and I can't move the console to share the ethernet port due to space and family issues.
Oh, I see. 360 adapters are Microsoft specialized. There is no 3rd party. I would recommend doing "Connection Sharing" with a laptop. Costs less than those adapters if you already have a laptop. All you would need to buy is another ethernet cord.
