Imp atient raises a good point; very high OG wort can overwhelm yeast, and cause either off-flavors or halt fermentation altogether.
That said, I can't imagine that you're actually adding SO much honey as to really increase the OG into the range that would harm your yeast. That level of OG is usually reserved for Dubbels (or Trippels, or Quadruppels.) If you're really concerned, make a starter for your yeast in order to ensure a really vigorous fermentation.
I agree with MaxHavoc; add the honey at flameout (it's sterile, and won't need to be pasteurized like your other ingredients) and be sure you mix well before pitching your yeast. Then, at the conclusion of primary fermentation, rack the wort onto your coco powder in your secondary fermenter. (Boil the powder in a cup or two of water, and chill it, obviously, to be sure it's sanitized.)