Dennis @ PerfectForms
We do have customers integrating with other CMS tools and AlphaTrust digital signature product. We also have a new web signature feature available. It lets the user sign the form with a finger (on a touch screen) or a mouse. I can have someone from sales to contact you about it if you are interested.
I am unaware of the technical specifications regarding Box CMS but will forward this request to Product Management to investigate if it supports open APIs or web services.