Can I restrict manual date input, So user will only be able to select date from pop up calendar ?

Can I restrict manual date input, So user will only be able to select date from pop up calendar ?

I want to restrict access for manual access in the date field.. 

My date field is called [Workshop_Date] in form [new_ws_entry] in my application called [new_ws_entry]   
No brackets

Its set up to have the user enter dates, either by clicking the calendar icon, or by manual entry.
I don't want manual entry as it leads to mess ups in the date field.
The users are from Canada and US, so when they enter dates.. its 2011/04/04  or 04/04/2011..


This leads to issues .. 

I have diabled the field, but it also disables any calendar input 
So I had called zoho and didn't get anywhere.. is this even possible ?

Any suggestions ? I have about used up any ideas I have left