[NTG-context] Minion Pro - em and slant?

I found a bunch of code that sets up Minion Pro (and Myriad) typefaces that seems to work (once I modified MinionPro-Italic and the rest to be MinionPro-It as it is on my system: http://pastebin.com/muSg4dZN However, neither \em nor \slanted make any change to the text. Since I'm basically blindly copying and pasting the typeface setup (is there a better way to use different fonts? The documentation is bewildering), I'm not sure what I need to do to get \em and \slanted working, though I really only care about the former... c -- Chris Lott