The only way you could do that was to connect - over the internet - with your home system.
And you'd already be connected to the internet - so? What's the reason for wanting to connect via your home account when you're away from home?
As das_stig mentioned, there is only two ways to connect to the internet when away from home:
1) Contact a cell provider, and get one of their USB dongles
2) Do what a lot of us do: Go into a place that offers wifi, and use their wifi. It might cost you $5 or so(depending on the place, but some require you to purchase something), but it's worth the price if you really need to go online away from home.