There is no way to do so in the current version. I tried seeing if it would be easy to switch it, but unfortunately the way Concrete5 implements that timepicker is really weird and difficult to understand (and of course not documented anywhere... grrr....)

I'll add this as a feature request to my todo list (but I won't be upgrading the addon anytime soon as I'm extremely busy these days).

Sorry, wish I had a better answer for you :(