Unfortunately there is no builtin way to modify the right shift key and map it to arbitrary keys. Fortunately, however, there is an app call "Karabiner" that grants you this functionality at an OS level. Meaning, it's not application specific.
The process is incredibly simple:
- Download Karabiner
- Go to the "Simple Modifications" tab
- Click "Add Item"
- From Key: right_shift, To Key: up_arrow as seen below: