Got the shift function working with xvkbd. I edited /usr/share/applications/hildon/xvkbd.desktop (also remove the one with the ~ extension hildon hates that) Can't get the size working right since hildon lacks a full window manager, but if you modify the exec line to

Exec=/usr/bin/xvkbd -geometry 180x100 -compact -always-on-top -minimizable

Close and then start the xvkbd you'll find that although the characters on the keyboard don't change (they always show uppercase) they do change in function. The problem with the only uppercase seems to be that Nokia has removed the standard X fonts (they ones that normally no one uses and so there is a need to put something in it's place working on the correct usage of the -font switch now to see if I can get Sans or Monospace to work instead.