How Much Yeast? I don't know! I would say to start off with hydrate the entire package, but only use half of the slurry. The fresh yeast will be hungry and as long as there is very little air in suspension you should be fine. However, the more I think about this, the less I personally would use. The reasoning is this. You don't want there to be a mini krausen in the bottle. that would be a bad thing! You just want enough yeast to consume the sugars for carbonation. I personally have had to much yeast in the bottom of a bottle before.
Like I said in the beginning of this post, I don't know. Is it 1/4, 1/3, 1/2, the smallest denominator may be the way to go in this instance. The worst thing that can happen would be it taking more time to carbonate.
Please let us know what you come up with and how it worked out for future reference. I will check Mr. Malty and post what I find later.
Cheers
Preston