Sorry I forgot to address your hardware question- as usual, Hover1 is right- you only need to plug the included expansion card into your PropScope and connect signals to the inner BNC... These forums are wonderful!
Now, how about a new challenge to solve TS's problem:
Design a simple circuit that:
- scales the PropScope's analog output to a higher voltage range- for example, 0-5V becomes 0-15V
- supports frequencies between .1 and 5MHz without introducing artifacts
- uses as few commonly DIP parts as possible