Disabling CF9 HTML datefield 'calendar icon'

Hey guys... i'm trying to disable a <cfinput type="datefield"> with javascript, of course i'm working with the HTML version of this control. So far my code looks like this:

<cfform name="TestingDisable" format="html" method="post" action="#CGI.SCRIPT_NAME#">

  <cfinput type="checkbox" name="agenda" onChange="document.evt_call.agendaDate.disabled=!this.checked">

  <span style="font-family:Verdana, Geneva, sans-serif; font-size:10px;">Schedule</span>

  <br/>

  <cfinput type="datefield" firstdayofweek="1" mask="mm/dd/yyyy" name="agendaDate" value="#now()#" disabled="disabled"/>

</cfform>

If you run this code it will show you the disabled calendar until you check the "agenda" checkbox... now, if you do not put a check on the checkbox the text part of the datefield stays disabled  but you can still pick a date clicking on the minicalendar icon that is located on the right.

Is there any way to disable the minicalendar clicking action for this control?

Ty in advance!