Please try this...
1. In Fusion, go to your virtual machine's Sharing settings (Virtual Machine menu > Shared Folders > Open Shared Folders Settings...)
2. Check the box to "Allow the virtual machine to open applications on your Mac".
3. Shut down (don't just suspend) your virtual machine, and exit Fusion.
When next you start up the virtual machine, you can use the "Open With..." dialogue (or the Folder Options Control Panel) to set the default application to use to open files of that type. Below the "Recommended Programs" section, at the top of the "Other Programs" section, you'll see the VMware logo and the line "Default Host Application". Select that, and you'll be able to use the Mac program assigned to open files with that extension from within the virtual machine.
