くしゅくしゅ　is an onomatopoeia word for states in which a thing is rumpled, creased, randomly folded, or the very act of creating such states. A good example is a rumpled paper (rumple up a piece of paper). The sound that is generated when you rumple up a piece of paper/aluminum foil/plastic bags is described as くしゅくしゅ, or くしゃくしゃ (which is much the same and most likely the origin of くしゅくしゅ) . While くしゃくしゃ can be used in any situation, くしゅくしゅ is used to describe something feminine (e.g. fashion, beauty) and thus popular among young girls today. As I remember, the first time we started to used this word (over 20 years ago) was to describe a hair accessory, named くしゅくしゅ or しゅしゅ. Nowadays it seems that くしゅくしゅ is heavily used in fashion. Further, girls are now using くしゅくしゅ in place of くしゃくしゃin non-fashion situations. (e.g. 顔をくしゅくしゅにするhave a big smile）This word makes everything soft, romantic, cute, cuddly, or anything girly and girls love, i.e. feminine.

In this particular case, the manufacture obviously employed this word to attract girls. A very simple translation would be “soft/air-ly/silkly foam”. However I suspect that the word is actually used as a verb here, in stead of an adjective for the foam. This is why I think that way:… I found blogs and reviews of similar products. There, almost all girls say “泡でくしゅくしゅする” and one even shows the picture of “a midst ofくしゅくしゅ(くしゅくしゅちゅー)” . See the picture at:
http://mi-www.at.webry.info/200805/article_15.html
So, it is used as a verb: “rumple up” your hair with the foam. I am not a native English speaker, so my suggestion might not sound right, but the best I can come up with would be: “froth up your hair with silky foam”. I don’t know if this phrase is attractive to girls in English-speaking cultures though…