What are the obstacles to pegging the value of bitcoin to an established stable currency?
The only way to fix an exchange rate is to constantly trade at this rate. This requires unlimited funds.

So assume you want to peg BTC against CHF as in your example. For simplicity, we aim at 1 BTC == 1 CHF. Here's a simple recipe.


Have unlimited Bitcoin and unlimited CHF.
Find a Bitcoin exchange. 
Offer to buy an unlimited amount of Bitcoin for 1 CHF/BTC.
Offer to sell an unlimited amount of Bitcoin for 1 CHF/BTC.
Observe how everyone will accept 1 BTC/CHF as the official rate.
If you run out of Bitcoin or CHFs, give up.