I put my exec.bin and grom.bin in:
This is one of the two paths that the emulator is set to look in. The jzintv and subfolder rom did not exist so I had to create them..
sudo mkdir jzintv
sudo mkdir jzintv/rom
and then I moved the exec.bin and gbrom.bin file from my intellivision rom directory:
sudo mv ~/Retropie/roms/intellivision/* /usr/local/share/jzintv/rom
Then I was able to launch my intellivision roms… hope this helps!