You can specify an email address to use for the forum badges, for when the forum is updated to include them, but AFAIK there is no way to directly link to a forum account.
Small issue though, I have been all over my Larian Vault account and I have seen absolutely nothing mentioning a forum badge even though I am a KS backer of Original Sin...
If you log in to the Larian Vault, click on 'D:OS Kickstarter' and then 'Your Choices & Input', any forum badges associated with your tier (starting with the $35 tier and above) or the Weresheep add-on (if applicable) should be listed there.
