How to set a parameter for a Form control

Hi,

I am doing a site in SF5. In this site, there are lot of pages having a common 
section displaying a contact form. Now this contact form is in html. The issue is that
all the fields in the html pages are same except a hidden field, say CostId.
Since this CostId is different for each html page, I need to create several html pages
with same fields with only difference being the value of CostId.

To avoid creating these html pages, I want to create a form control which accepts
CostId as parameter. How can this be done? ie. I would like to be able 
to drag/drop this form control on the page and then set the CostId.

The functionality is amost similar to FormsNotification scenario. ie instead of Email settings, I need to set CostId while dragging the control to the palceholder.

Can anyone please help me.

Thanks,
Surya.