I have scoured the internet, among which Cemetech, for the Software, Password and License Code of the Casio Picture Conversion Engine and I finally found all three.

For the software you can go to https://edu.casio.com/download_service/download/private/form.html, if the site goes down, I have the .exe on my computer.
You'll have to download 1.01.

It'll ask for a password now, for both windows and mac, this is: "pictureplot"
After completing the first few steps of installation it'll ask for a License Code, for Windows this License Code worked: "ZSTC-4W9R-​874FYYX9-BCA3YN623".
I don't have a mac, so I don't know if it works for mac.

You'll also need Quicktime 7 or later, this you can download for free from Apple (also on a Windows computer).

Now you can convert almost any picture or video to "g3p" or "g3b" file formats.

The version is now 2.0 and "pictureplot" no longer works. Does anyone have the latest password and license code?

SourceCoder even takes one step further for free: The pictures converted with it are compatible with the fx-CG10, unlike with the official Casio tool.

I've searched for quite a while, but couldn't even get past the password firewall (even with Chrome DevTools shenanigans). I think you should keep using V1.01 or use the converter the other commenter suggested.

I can confirm that this licence key while works fine for Windows version, it can't be used for the Mac version!

For Windows only.
ZSTC-4W9R-​874FYYX9-BCA3YN623

I was going to say this myself! Just use the free SourceCoder converter: http://sc.cemetech.net

As the site admin said, I would recommend using the SourceCode converter, but if you want to download this program anyway: I found the password and license key for version 2.

Same website: https://edu.casio.com/download_service/download/private/form.html

Password: cp2picture
After downloading and installing it will ask for a License Key.
License Key: ULQ3-5WKS-LS2F2ZEX-E79XK7JNL