I figured it out. I had to manually edit a setup file.
I had to edit
~/Library/Preferences/VMware Fusion/preferences
I turned off all shortcuts and added this line
pref.keyboardAndMouse.profile0.mapping18.enabled = "TRUE"
pref.keyboardAndMouse.profile0.mapping18.fromHost = "0x137"
pref.keyboardAndMouse.profile0.mapping18.toGuest = "HideApplication"
this maps "print screen" to HideApplication.
to figure out the keycodes for the "fromHost" field I used the existing keyboard preferences pane. In the "key mappings" tab you can enter custom keystrokes. the preferences file will be updated. You must take the "fromHost" for the "key mappings" tab entry you just created and change it's toGuest field to point to the Fusion Shortcut you desire. I don't know if there are more available Fusion Shortcuts, thery might be related to AppleScript identifiers.
I set all keys other then PrintScreen to pass straight through to the VM. With this change, I am very very happy with VMWare Fusion.
