I don't understand the question. Importances and WTP are different entities that you derive from the utilities. To the extent relative importance matters in the WTP calculation it is already included in the utilities upon which the WTP calculation is based. I don't think there's the extra step here that you're seeing.
By the way, if you do use the share route I described last in the earlier answer, make sure to add make it competitive - that is rather than compare head-to-head the concept with and without the improvement and find the price where they're each 50%, make a realistic competitive set of products which includes the product which you want to improve, but without the improvement and without changing the price. Note it's share. Now add the improvement and keep raising the price until you hit that share again - that's a better estimate of the equalization price because it more realistically accounts for competition.