Well, we don't condone or support that. Using the beta when you are not a developer is against the spirit of the agreement and you can't strictly obtain it legally. However, once your device is registered, it is registered regardless of what you do with it.
You are in for a world of pain when you jailbreak it though, unless you are an experienced jailbreaker, and from the sounds of your question that doesn't seem to be the case. It has been clearly stated that the beta IOS5 tethered jailbreak is extremely flaky and only for developers of JB apps to allow them to work on updates for IOS5 compatibility.
As this is a jailbreak query, I'll move the thread to the hacking section.