Spot on.  :) Just run it as admin and point it to your FSX folder. Then try again with loading the 707 in FSX, but make sure to enable that special panel.cfg file for the Civa operation.

CIVA_panel.cfg in \SimObjects\Airplanes\CS_B707-300\panel has to be renamed to panel.cfg. Make a backup of the old file, just in case.

For tweaking the installation, refer to Mark's tips on moving the one gauge entry. Or take a look at the twin INS installation. But the first step will surely be to check if the basic stuff is working, so you are right on track with the Civa installer.  :)