With a 396, I just create a new conventional system, then create a typical group. Enter the frequency as a conventional frequency in that group. You don't need to do anything with respect to P25. The radio will know it's a digital channel when it stops there.
I would imagine that a 296D would not be that much different (with the exception of using banks versus dynamic memory).
I noticed this inadvertantly shortly after I got my 396. Details of what I found are
here.
Good luck,
Steve