I was looking at doing this a few years ago, I would suggest that you make the arrangements through someone in Corfu, I am sure Lynne or Nathan will correct me but I believe it is something that Agni Travel can offer. Also CV or Meon Travel will help, but I think that they have the arrangements made by someone outside the company. I am sure the name of am organisor will be posted by someone here.
Civil ceremonies are possible out there as they are here, butI am not sure about the licensing of venues.
Also one important factor is that you have to be resident on the Island for 10 days prior to the ceremony (at least you did when I was looking!) If you want a holiday afterwards as your honeymoon, you are really looking at a 3 or 4 week stay.... So worth doing just for that!
I have to admit that I went off the idea eventually and am now getting married in the UK and flying out to Corfu the same day.