Wormwood (Absinthe) Wine

So I've decided to make an Absinthe wine, thinking of using a Reisling or Sav Blanc base then infusing it with the worm wood.

so a few questions for anyone with experience with Herbs or Absinthe..

1. How much should I use in a 5 gal batch, god knows I don't want to put in too much

2. should I add the herbs during primary fermentation or wait until it's done fermenting?

3. Anyone know a reputible place to buy it? I found this http://www.frontiercoop.com/products.php?cn=Wormwood+Herb

I plan to buy some seeds and grow my own at some point but would like to make some with a plant already grown..

I did a quick Google search and found quite a few reference for this wine. most use Everclear or wine spirits. May be difficult with grape wine . one idea use spirits and then blend with grape wine. this would control total flavor.