This Works
serv from the Parallels Team wrote "Release Input shortcut can be changed in OS X System Preferences > Keyboard > Keyboard Shortcuts > Application Shortcuts. Click + (plus), select Parallels Desktop application, Menu title is "Release Input" (without quotes)."
This actually worked. I tried to map the release input to crtl+alt but it wouldn't let me, so instead I mapped it to crtl+r and that seemed to do the trick. It's not the preferred shortcut but since I only use coherence mode, it works just fine.
I didn't like the option to use the fn+ctrl+opt shortcut, since my Mac is docked and the lid is almost always closed.