I am a US citizen married to a Swiss citizen. We live together permanently in the US. I would like to work for several weeks in the summer in Switzerland (assuming I can find a position).

What do I need to do (if anything) to get a legal permit to work in Switzerland?

You have to ask the nearest consulate.

They will want marriage certificate, birth certificate, etc.

You will receive a permit, but it is just a formality.

Maybe things have changed since I did the same many many moons ago but in my case I didn't receive a permit to work in Switzerland while still in the States. What I got was permission to come to Switzerland to search for work, the permit came when I found a job. And yes, as HollidayG stated, it's just a formality.

Was your marriage before the adherence of Switzerland to the European Convention on Human Rights and Fundamental Freedoms, and specifically Art. 8(1), right of family life?

The spouse of a Swiss need not work. S/he may live a life of leisure and/or childraising if desired.

For what it is worth, the ECHR was in force and effective in Switzerland on 28/11/1974