If I'm understanding this correctly, you want to "hand code" a few lines and then verify them. By that, I mean add in something like:
G0 X1. Y0.
G1 X.5 F20.
in the editor
If so, then no, it won't work. It needs to be done through MasterCam toolpaths. It is possible to backplot the NC code by using something like Discriminator. It's available as a free download.
Hope that answered your question