this topic scared the hell out of me at the beginning, then i tried and thank god everything works just fine for me.
as long as google voice works and that i can use my old iphone 3g(jailbroken & unlocked) as an hotspot(trough blutooth) i'm ok. basically fastweb is gifting me a sim card with 1gb per month for free, and i'm willing to use it as my tablet 3g plan.
i suggest you to use your cellphone as an hotspot too, it's the easiest way to do what you wanna do.( of course if you have an internet plan on your phone)
i don't use the internet plan i have on my galaxy cause internet plans in italy aren't unlimited(i have 100MB of data per day)