Basically what you have to do is join for FREE the www.molto.com (in sl, type that on the search bar and there you have it)and then grab a pair of glasses that will work as a sign for the vendor to give you the prize, other way I don't think it'll work.
My first findings have been DeeTaleZ and Gawk! See the pics and the credits below:
The lingerie set and the hair shave unisex tattoo are the gifts from DeeTalez. The black outfit can be found at Gawk.
For more stores participating on the hunt see this link http://moolto.ning.com/group/mooltosistershunt