Lon,
Have you installed the IPAC Configuration Utility software that came with your card? It's really helpful in terms of customizing buttons and such. There are two ways to manipulate button settings within this software. I personally find it easier to use the "Table" version (versus the button layout version)...you will see small check-boxes as to how you want to see the layout. From there (the Table), you can easily assign key assignments.
I would create a new IPAC file when in this Utility to mess with. Depending on what frontend you use, you should be able to launch this IPAC file with the frontend.
Regarding your wanting to change the shift function...what are your reasons for doing this? Do you want to change this because you want to set up individual buttons to allow for the use of the Pause, Escape, Tab, and Enter functions?