For either of these, you need to do this first:
1) Click on the "Filter" drop down in the bottom left, and
2) Select "Show Library Elements"
This will make all the core library elements visible in your tree. They will show up as gray, as they are not directly editable - yet.
For the "jump" case, you can do one of two things:
1) Under "Commands", find the "jump" verb. By default it prints out the DefaultJump template. You can modify the command script directly. First click Copy in the top right to copy the command into your game. It will no longer be gray in the left pane after that. Then you can change the text directly. You can change it from "expression" to "message" and then just type in the text you want.
-- or --
2) Modify the DefaultJump template (leaving the command alone). Templates are under Advanced, and there are a lot of them. But once you find the one called "DefaultJump", copy it into your game with the "Copy" button and then modify the text.
For the "look scav" case, you can modify the "lookat" command to generally accept "look" as well. Again, with library elements shown, find "lookat" under "Commands". Copy it into your game with the "Copy" button. Then add "look #object#;" to the front of the pattern. Your pattern will then look like:
look #object#; look at #object#; x #object#; examine #object#; exam #object#; ex #object#
This does mean that the plain "look x" pattern will work with all objects, not just the scavs.