Pre-fill in a lightbox

Is there a way for me to open a lightbox on the scheduler and pre-fill in the description, start and end times and other drop down selections???

I have an external view page where information is entered in to create an appointment, then I want to place an icon to put the appointment onto the scheduler. I know how to link to a specific date on the scheduler for an external page, but is there a way to make the lightbox come up and pre-fill in the fields so most of it is all ready for the user to just save onto the scheduler after reviewing it???