The value for the PushOnClick property on an image is the ObjectID of a Script button. So, first create a script button with a script that does what you need. Then, you can get the button's object ID from its properties pop-up. It is the string at the top that starts "Personas/..."
You can just click on that text to copy it to the clipboard, and then paste it into the PushOnClick property of the image. Like this:
Then clicking on the image will be just the same as clicking on the script button. Once you've done this, you can hide the script button since the user doesn't need to see it (unless you want it visible as well as the image, in which case, leave it).
Steve.