I've worked with ICVolunteers quite a few times, both with the Switzerland office and France office as well), and they're great. I have even had the chance to work on projects with them where the organizations paid for our travel expenses and accommodations, and our meals. I met interpreters in France, England, Spain, Belgium, Chile, etc. who were working for them as well, and made friends, new business contacts, and gained experience thanks to which I have been hired by other NGOs and financial institutions.
I think with ICV you just really have to let them know that you're willing to travel and email them whenever you see new events on their website. I know that for two recent conferences, they flew in people from Paris, Barcelona, and Cambridge, so I'm sure you'll get a chance to work with them if you let them know you're very interested.