I took my recipe from Michael Laiskonis' blog and tweaked it for white chocolate, and it seemed to work well enough. You may want to play with it a bit though.
8 sheets gelatin
80g water, cold
280g heavy cream
420g granulated sugar
200g white chocolate
1. Bloom gelatin in first measurement of cold water. Reserve.
2. In a large saucepan, combine cream, second measurement of water and sugar. Bring to a boil and cook to 103oC/217oF.
3. Remove from heat and whisk in white chocolate, followed by bloomed gelatin and any unabsorbed water.
4. Process with an immersion blender. Allow to cool to 40oC/104oF before glazing, or chill completely for later use.
You can see pictures of the result here: http://mcswiggendesserts.blogspot.com/2010/04/work-in-progress.html