Can I have a custom image as a "click to pop ONTRAform" option?

Yes, you can use the click to pop code and custom it to include an image.  Here are the step-by-step instructions:

1. Start with a hosted image; you can upload it to the ONTRAPORT File Manager, or host it elsewhere. Copy the URL of the hosted image to the clipboard.
2. Navigate to Forms and Open up your ONTRAform
3. Click on the Publish Button and select the "Click-to-Pop" option.
4. Copy and paste this code into the "Link Text" area <img src="image_url.png" />
5. Replace what is in between the quotes with your copied URL so it looks like this:
   
   
   
   
6. Copy the form code to your clipboard
7. Navigate to http://htmledit.squarefree.com/ for a real-time editing experience. Or, if you feel comfortable enough with coding, you can paste it into a notepad of your choice.
8. Paste in your form code. It should display the hosted image you specified (in this example, it is the red "Start now" button):
   
   
   
   
9. Delete all code starting after <a and ending before href as this is the designated code for the button border and styling. Here's an example:
   
   
   
   
10. Your final product should look like this with your image being the button and the old border having been deleted: 

<a href='javascript://' data-opf-trigger='p2c25283f58'><img src="http://blog.conqueryourdebt.org/wp-content/uploads/2013/05/Startnow_button_resized.jpg" /></a><script type='text/javascript' async='true' src='https://app.ontraport.com/js/ontraport/opt_assets/drivers/opf.js' data-opf-uid='p2c25283f58' data-opf-params='borderColor=#fff&borderSize=5px&formHeight=583&formWidth=40%&popPosition=mc&instance=n498752995'></script>

Now you should be ready to paste that code to your website.