You need to call Verizon and explain to them that you are going overseas and that you want to use a pre-paid SIM card that you'll purchase in Switzerland. Once you have reached the Global services dept. they will look at your account and if it's in good standing they will walk you through the process of unlocking your SIM.
Then, you can put in any GSM SIM card and set the phone to global mode (Start - Settings - Personal - Phone - Network - Switch from CDMA only to Global or GSM/UMTS Only)
Once you get to wherever you are going you can buy a prepaid GSM SIM card and stick it in. Your phone will pick up their service. You have to make sure to ask them about data charges, text messages, etc. and choose your plan accordingly. If you are going to use data then they will have to show you how to configure the data settings.
Once you have spoken to VZW about unlocking they will probably try to sell you on a global roaming plan which may not be too bad for you to consider. Hear them out and ask them the same questions that you would ask here. I for instance would want to know if I'm using an international GSM card will I incur any data charges on my VZW bill, etc. A good rep will tell you everything you need to know about roaming.
If you only want the phone for making calls in Europe then it's a great idea to just get the SIM card and use only GSM band but it's still best to let VZW know that you are roaming so you know what to expect.
There are other threads that go into this, read
HERE for one.