I think your best bet would be to have it re-tapped. Check to see if there's a cue maker in your area. I'd do it for free for you as I have a 3/8-10 tap. A cue maker probably would charge you just a few bucks.
Try any of the lubricating methods mentioned above before the tapping. My guess is that you will not be happy with how lose it will be once tapped. I use the carnuba cue wax myself as I always have it on hand. But all the others mentioned should be successful also.