Hi Ifranks,
I contacted my swiss local insurance providers (2 of them) and they told me that is is not customary for them to issue short-Term Liability insurance policies, particularly if you do not live in the country (Switzerland).
You may need to get an international insurance, there are several companies out there. I found this link that has some information.
-www.internationalinsurance.com/news/personal-liability.php-
In the past I used Allianz when having a 2 month assignment abroad and it did include liability. (BTW I do not have any link to this company other than being a past customer of them).
Hope it give you some direction.
Please share your findings if you find an option.