prevent too fast typing, how to?

[Peter Alcibiades]

I'd like to do the following.  If 000 is typed at superhuman speed, only the 
first 0 should make it into a field.  But if 000 is typed at normal human 
rates, all three should.

Can you think of any way to do this?

The problem is a keypad with a 000 key right next to the 0 key.  All it does 
is keypress followed by keyrelease, superfast, three times.  I know the users 
are going to press it by mistake, and then they are going to get very 
flustered when they see their amounts in thousands not tens.  So I'd like 
some way to make it just result in one 0 being entered.

Grateful as ever for any hints!

Peter