I have never brewed a Mead, and am a relative newcomer, but I can offer some suggestions and others can correct me...
You can always add lactose (milk sugar) to your brew, because it is unfermentable and hence only adds sweetness. (This is used in milk/sweet stout).
Others add Splenda. I am not sure the quantity but I am sure someone will chime in.
The Montrachet yeast seems a very popular yeast, but it does attenuate well, so if it does its job it is going to convert most of the fermentable sugars. You could look for a wine yeast with a lower attenuation rate.
I do believe, though, there are things you can add to wine to cause the fermentation to stop, which you wouldnt do in a beer due to the potential off flavors it may cause... though I may be wrong, maybe you dont do this in windes either...
As I am going to brew some fruit wines myself as soon as my fermenting buckets empty I would love to hear some answers to this question too... And due to my diet I cannot use the lactose, and if there is a way to avoid adding Splenda I would appreciate it, so alternative methods are something I am interested in studying...