Customization In Date Picker

Hi,

I wanted to give some validation over the date picker parameter. For example if I have selected 15-10-2014 as a start date, so for end date user should not be able so select date less than 15-10-2014. Currently I am using below formula for restricting the report to run but I wanted to be able to achieve something like the dates before end date should be disable to select.

=IF([startDate] >= [endDate];Error("End Date Cannot be Less than Start Date"); [endDate])

Is there any way to do this by doing some tweaks with jars or any js?
Currently I am running
Pentaho 5.0.1 EE
Java 1.8
Windows 8.

Thanks