I got the hub off of eBay, so the seller was the guy that got me into this bind.
I tried a strapwrench, but that didn't work so hot. Not enough leverage.
It's a pretty big cog, 20t and it's solid on the sides so I can't get any spokes in that side.
I ended up clamping it in a vise, holding it with the strapwrench and gave it two bumps with an impact wrench and the cog came spinning off. Cog is a bit dented, but functionally okay. Looks like I'll be building up the wheel tonight!
Thanks a bunch for all the ideas!