The web information is here:
http://www.eda.admin.ch/eda/en/home/...ontentPar_0014

QUOTE:
Work Visa for US-citizens and other nationals for which an authorization has been given directly in Switzerland
If your employer has applied for your work permit in Switzerland and it has been granted, you still must apply for a visa to enter Switzerland with the competent Swiss representation abroad.
To apply for the visa, you must submit the following documents to the competent Swiss representation:

1. One national (type D) visa application form, fully completed and signed by the applicant. For stays up to 3 months or authorisations for a 120 day visa, the regular Schengen visa application form should be used. Applications which are not duly completed, dated and signed will not be accepted. Please also indicate your e-mail address and a contact phone number in case additional information is required.
2. Two passport photos per applicant (very strict requirements, please consult the details on the webpage)
3. Applicant’s valid original passport, plus a copy
4. Visa fee (only money order or cash)
5. If applying by mail: one prepaid, self-addressed, return envelope with a tracking number