Z1U Mic Mount
 

I used the Sony Z1U Mic Mount parts. I ordered it as a kit on ebay a couple of months ago. The guy told me it was just the Z1U Mic Mount parts along with a little spacer added to make it fit on the FX1. I'll take a side pic to show you. Installation was very very easy and i'm very happy with it. My only gripe is that the spacer is a dark gold color. I would have hoped it would have been black or dark gray to match the camera.

Here's a link to some info:
http://www.videomaker.com/forums/viewtopic.php?t=2341

It does not look like the kits are on sale on ebay anymore though but i'm sure if you really wanted to, you could find all the parts you needed (including the spacer) for much cheaper.